Search

There are few studies about the effect of turmeric powder on the skin pigmentation of fish in the literature. This study was conducted to research body and tail pigmentation and growth performance of Pseudotropheus acei (Regan 1922) fed supplemented diets with different ratio turmeric (Curcuma longa) powder. Five diets were prepared by adding four different ratios of turmeric powder (T1: 1%, T3: 3%, T5: 5%, and T7: 7% ) to C: control diet (without turmeric powder). A total of 75 broodstock (mean weight 6g) were randomly stocked (4♀:1♂) in 15 aquariums (70x30x40cm), with three replications. The fish were fed twice daily at 8:30 and 20:30 with the diets supplemented turmeric as ad libitum during the 90 days. At the end of the experiment, the body and tail pigmentation of P. acei significantly increased with increasing turmeric rate in diets (P

Understanding the origins of phenotypic diversity among closely related species remains an important largely unsolved question in evolutionary biology. With over 800 species, Lake Malawi haplochromine cichlid fishes are a prominent example of extremely fast evolution of diversity including variation in coloration. Previously, a single major effect gene, agrp2 (asip2b), has been linked to evolutionary losses and gains of horizontal stripe patterns in cichlids, but it remains unknown what causes more fine-scale variation in the number and continuity of the stripes. Also, the genetic basis of the most common color pattern in African cichlids, vertical bars, and potential interactions between the two color patterns remain unknown. Based on a hybrid cross of the horizontally striped Lake Malawi cichlid Pseudotropheus cyaneorhabdos and the vertically barred species Chindongo demasoni we investigated the genetic basis of both color patterns. The distribution of phenotypes in the F2 generation of the cross indicates that horizontal stripes and vertical bars are independently inherited patterns that are caused by two sets of genetic modules. While horizontal stripes are largely controlled by few major effect loci, vertical bars are a highly polygenic trait. Horizontal stripes show substantial variation in the F2 generation that, interestingly, resemble naturally occurring phenotypes found in other Lake Malawi cichlid species. Quantitative trait loci (QTL) mapping of this cross reveals known (agrp2) and unknown loci underlying horizontal stripe patterns. These findings provide novel insights into the incremental fine-tuning of an adaptive trait that diversified through the evolution of additional modifier loci.

This study was conducted with aim to investigate the effects of Isatis tinctoria leaves extract on growth performance, pigmentation and protection against Aeromonas hydrophila of Pseudotropheus acei. Five diets were prepared by adding four different ratios fish woad extraction (Woad: W1: 1%, W1.5: 1.5 %, W2: 2 %, W2.5: 2.5% and C: control diet 0 %). Three replicates were conducted for each treatment. One hundred twenty fish and 15 tanks (80 x 30 x 80 cm) were used in recirculating system. In the end of 90 days, there were no differences in terms of weight gain, FCR and SGR of Pseudotropheus acei feed with diets added with different levels of Isatis tinctoria extraction compare to control group. Isatis tinctoria extract was not found effect on survival rates in Pseudotropheus acei after A. hydrophila infection. However, there were no differences on pigmentation of Pseudotropheus acei. Isatis tinctoria extract administration did not provide protection against Aeromonas hydrophila infection.

Bu calisma, Pseudotropheus acei' baliklarinda yemlere yuksek seviyede kirmizi biber ilavesinin buyume performansi, renklenme, histoloji, intestinal mikroflora ve Aeromonas sobria 'ya karsi hastalik direnci uzerine etkilerini belirlemek icin yurutulmustur. Kontrol yemine % 15 oraninda biber unu eklenerek Iki izonitrojenik (% 37 ham protein) ve izokalorik (3831kcall / kg enerji) deneme yemleri hazirlanmistir. Besleme denemesi, akvaryumlarda (100 L) uc tekerrur olacak sekilde 90 gun beslenerek yurutulmustur. Denemenin basinda, her akvaryuma yirmi balik (baslangic ​​agirligi 0.06 g) stoklanmistir. Deneme sonunda,yemlere kirmizi biber ilavesi ile beslenen baliklarin agirlik kazanci, yem donusum orani, spesifik buyume orani ve yasama orani uzerine onemli bir etkisi olmamistir. Ancak, kirmizi biber iceren yemlerle beslenen disi baliklarin kuyrugunda pigmentasyonun onemli derecede arttigi gorulmustur. Yemlere yuksek seviyede kirmizi biber eklenmesi hicbir organda patolojik bir bulguya neden olmamistir. Kirmizi biber, A. sobria enfeksiyonuna karsi korumada onemli bir farklilik gostermemistir. Kirmizi biber grubunda Aeromas ve Pseudomonas sayilari kontrol gruplarina gore anlamli derecede dusukt bulunmustur.

This study was conducted to determine the effect of turmeric powder dietary supplementation on the histology of visceral organs and reproductive performance of Pseudotropheus acei. The fish were fed dietary additions of 0%, 1%, 3%, 5%, and 7% turmeric powder. Each treatment was replicated three times. There were one male and four female fish with a mean weight of 6 g in each replicate. The fish were fed ad libitum for 90 days. There were no differences in fertility rate, fecundity rate, hatching rate, egg diameter, and larvae survival rate among groups (P < 0.05). Ovulation frequency and the percent of spawning broodstock were less in the 7% and 5% turmeric-supplemented group (P < 0.05), while there were no effects of treatment in the 1%, and 3% groups compared with the control group. Observations in histopathological examinations indicated there were normal tissue structures in the control, 1% and 3% turmeric-supplemented groups, while the addition of 5% and 7% turmeric induced a degeneration of and decrease in number of observable ovarian follicles. In addition, there was a normal liver structure in the control and the 1% and 3% turmeric-supplemented groups and slight to severe lipidosis in the 5% and 7% turmeric-supplemented groups. Also, the supplementation of larger amounts of turmeric induced enteritis and the slight to severe side effects on the relevant organs. These results indicate that supplementing of diets with turmeric powder in amounts of 5% and 7% suppressed ovarian follicle development, and extended periods between times of spawning which resulted in subfertility of broodstocks.

Female color polymorphisms are common in the cichlid species radiations of Lake Victoria and Lake Malawi. According to theory, when a population harbors variation in sex-determining factors, polymorphism in female-linked coloration might generate individual variation in male mating preferences for female color morphs. We tested whether individual males exhibit consistent mating preferences for female color morphs in the Lake Malawi cichlid Pseudotropheus (Maylandia) 'zebra gold', a species polymorphic for female coloration and sex determination. We also explored whether male mating preferences could be predicted by maternal coloration or were acquired by imprinting on siblings' coloration. We found large individual variation in the strength and direction of male preferences for sex-linked female color patterns. Male mating preferences could be predicted by the mother's color morph and were not affected by visual imprinting. These findings represent the first evidence of male choice on sex-linked female coloration in a Lake Malawi cichlid. Our analysis indicates a strong genetic component to male preference for female coloration and large individual variation in the strength and direction of male mating preferences. Within-population variation in innate mating preferences might have important implications in cichlid fish species radiations. Copyright 2008, Oxford University Press.

Pseudotropheus livingstonii (Boulenger 1899) (Fig. 2) Tilapia livingstonii Boulenger 1899 Pseudotropheus williamsi (non-G��nther).��� Regan 1922 Pseudotropheus livingstonii, Trewavas 1935.��� Konings 2007 Pseudotropheus elegans (non-Trewavas).��� Ribbink et al. 1983 Metriaclima livingstonii.��� Stauffer et al. 1997 Material examined. Pseudotropheus livingstonii BMNH 1863.11.12.22, holotype, 55.7 mm SL, Zambesi Expedition, Lake Mala&wcirc;i; PSU 4925, 19, 64.3���114.4 mm SL, Cape Maclear, 14��05��� S, 34��54���E, Lake Mala&wcirc;i. Diagnosis. Pseudotropheus livingstonii is distinguished from all other members currently in Pseudotropheus (Konings 2007), except P. crabro, P. demasoni, and P. saulosi, by the presence of five or fewer vertical bars below the dorsal fin. Most Pseudotropheus species either have no bars or have greater than five below the dorsal fin. Pseudotropheus livingstonii is distinguished from P. crabro, P. demasoni, and P. s au l os i by a pale yellow to hyaline dorsal fin vs. dorsal fin heavily pigmented with black. Description. Principal morphometric ratios and meristics for holotype and for specimens from population at Cape Maclear in Table 1. Medium-sized to large mbuna, ovoid body (mean BD 31.4% SL) with greatest depth between fourth to sixth dorsal spine. Dorsal body profile with gradual curve downward posteriorly, more pronounced towards caudal peduncle; ventral body profile almost straight between pelvic fins and base of anal fin with upward taper to caudal peduncle. Dorsal head profile rounded, with smooth curve between interorbital and dorsal-fin origin; horizontal eye diameter (mean 32.0% HL) greater than preorbital depth (mean 19.6% HL); eye (along horizontal axis) in center of head; snout straight to slightly concave in some individuals; isognathous jaws; tooth bands with 4���5 rows in upper jaw and 3���5 rows in lower; rows continuous through symphyses; teeth in anterior outer row bicuspid with posterior lateral teeth primarily unicuspid, teeth in inner rows tricuspid. ......continued on the next page Dorsal fin XVII���XIX (mode XVIII) and 9���10 (mode 9). Anal fin III and 8���9 (mode 8). First 4���5 dorsal-fin spines gradually longer posteriorly; fourth spine about 2 times length of first spine; last 13 spines slightly longer posteriorly; last spine longest, about 3 times length of first spine; rayed portion of dorsal fin with subacuminate (females) to pointed (males) tip, third or fourth ray longest, to approximately �� length of caudal fin in females and approximately �� length of caudal fin in males. Anal-fin spines progressively longer posteriorly; third or fourth anal-fin ray longest, �� length caudal fin in both sexes; 0���3 small yellow spots on posterior part of anal fin in females and 0���6 yellow spots on posterior part of anal fin in males. Caudal fin subtruncate to slightly emarginate. Pelvic fin to first or second spine of anal fin. Pectoral fin moderately long and wing-shaped with upper pointed tip, length to vertical line through base of 12th or 14th dorsal-fin spine. Flank scales ctenoid with abrupt transition to small scales on breast; 32���35 lateral-line scales; cheek with 3���4 (mode 4) rows of small scales; caudal fin with tiny scales to �� length; no scales on other fins. Gill rakers on first ceratobranchial 9���12 (mode 11). Recently captured fish with dark brown head, white gular region with gray blotches; black spot on opercle with reflected blue highlights. Laterally brown with 4 dark brown bars from dorsal fin to belly. Caudal fin with yellow rays and clear membranes. Anal fin brown anteriorly to first or second ray, hyaline posteriorly; 0���6 yellow ocelli in rayed portion. Pectoral fins with yellow rays and clear membranes. Pelvic fins black anteriorly, hyaline posteriorly. Female coloration similar to male, not as vivid., Published as part of Stauffer Jr, J. R., Konings, F. & Ryan, T. M., 2016, Redescription of Pseudotropheus livingstonii and Pseudotropheus elegans from Lake Mala��i, Africa, pp. 169-178 in Zootaxa 4154 (2) on pages 172-174, DOI: 10.11646/zootaxa.4154.2.4, http://zenodo.org/record/255176, {"references":["Boulenger, G. A. (1899) A revision of the African and Syrian fishes of the family Cichlidae, Part II. Proceedings of the Zoological Society of London, 1899, 98 - 143.","Regan, C. T. (1922) The cichlid fishes of Lake Nyasa. Proceedings of the Zoological Society of London, 1921, 675 - 727.","Trewavas, E. (1935) A synopsis of the cichlid fishes of Lake Nyasa. Annals and Magazine of Natural History, 10, 65 - 118. http: // dx. doi. org / 10.1080 / 00222933508655026","Konings, A. F. (2007) Malawi cichlids in their natural habitat. 4 th Edition. Cichlid Press, El Paso, Texas, 424 pp.","Ribbink, A. J., Marsh, B. A., Marsh, A. C., Ribbink, A. C. & Sharp, B. J. (1983) A preliminary survey of the cichlid fishes of rocky habitats in Lake Malawi. South African Journal of Zoology, 18, 149 - 309. http: // dx. doi. org / 10.1080 / 02541858.1983.11447831","Stauffer, J. R. Jr., Bowers, N. J., Kellogg, K. A. & McKaye, K. R. (1997) A revision of the blue-black Pseudotropheus zebra (Teleostei: Cichlidae) complex from Lake Malawi, Africa, with a description of a new genus and ten new species. Proceedings of the Academy of Natural Sciences of Philadelphia, 148, 189 - 230."]}

Pseudotropheus elegans Trewavas 1935 (Fig. 3) Pseudotropheus elegans Trewavas 1935 Metriaclima elegans.��� Stauffer et al. 1997 Pseudotropheus livingstonii (non-Boulenger).��� Konings 2007 Pseudotropheus sp. ���acei���.��� Konings 2007 Material examined. Pseudotropheus elegans, BMNH 1935.6.14.127, holotype, 85.4 mm SL, Chilumba Bay, Lake Mala&wcirc;i; PSU 11394, 12 specimens, 43.4���63.1 mm SL, Chitande Island, 12�� 23.764'S 34�� 15.275'E, Lake Mala&wcirc;i. Diagnosis. Pseudotropheus elegans is distinguished from all other members currently in Pseudotropheus, except P. williamsi, by a pale yellow to hyaline dorsal fin and by the absence of distinct vertical bars below the dorsal fin. Most species of Pseudotropheus either have distinct bars below the dorsal fin or a dorsal fin with black pigment. It is distinguished from P. williamsi by the absence of two horizontal lines of black dots on the flank. Description. Principal morphometric ratios and meristics for holotype and population from Chitande Island in Table 1. Medium-sized mbuna, ovoid body (mean BD 31.6% SL) with greatest depth at about 6���7th dorsal spine. Dorsal body profile with gradual curve downward, more acute towards caudal peduncle; ventral body profile slightly convex between pelvic fins and base of rays of anal fin with upward taper to caudal peduncle. Dorsal head profile round, with continuous curve between interorbital and dorsal-fin origin; horizontal eye diameter (mean 36.7% HL) greater than preorbital depth (mean 16.3% HL); eye (along horizontal axis) in anterior half of head; snout straight; jaws isognathus; tooth bands with 4 rows in upper jaw and 3���4 rows in lower; teeth in anterior outer row bicuspid with posterior lateral teeth primarily unicuspid, and teeth in inner rows tricuspid Dorsal fin XVII���XIX (mode XVIII) and 8���9 (mode 9). Anal fin III and 8���9 (mode 8). First 4���5 dorsal-fin spines gradually longer posteriorly with fourth spine about 1�� times length of first; last 13 dorsal-fin spines increasingly longer posteriorly with last spine longest, about 2 times length of first; soft dorsal fin with subacuminate tip, third or fourth ray longest, to approximately �� length of caudal fin. Anal-fin spines progressively longer posteriorly; 3rd or 4th ray longest, to base of caudal fin in both sexes; 1���3 small yellow spots on posterior part of anal fin. Caudal fin subtruncate to slightly emarginate. Length of pelvic fin to first spine of anal fin. Pectoral fin short and paddle-shaped, length to vertical line through base of 10���11th dorsal-fin spine. Flank scales ctenoid with abrupt transition to small scales on breast; 32���33 lateral-line scales; cheek with 3 rows of small scales; caudal fin with tiny scales to �� length; no scales on other fins. Gill rakers on first ceratobranchial 10���12 (mode 11). Recently captured fish with gray head, white gular region, and black opercular spot. Laterally gray ground coloration; scales with green outline; breast and belly gray. Dorsal fin pale yellow to hyaline. Caudal fin with two ventral rays and membranes black; remainder clear with faint white spots. Anal fin black with white marginal band; 1���3 yellow ocelli in rayed portion. Pectoral-fin rays clear; pelvic-fin rays black anteriorly, remainder clear. Coloration of female similar to male. Remarks. The holotype of P. elegans and a population of this species collected from Chitande Island were compared morphologically to the holotype of P. livingstonii and a population of P. livingstonii collected from Cape Maclear. A plot of the sheared third principal components of the morphometric data against the first principal components of the meristic data (Fig. 4) showed that the holotype of P. livingstonii grouped within the minimum polygon clusters and the 95% confidence ellipses formed by the meristic and morphometric data from those individuals collected at Cape Maclear. A plot of the sheared second principal components against the sheared third principal components (Fig. 5) showed that the holotype of P. elegans grouped within the minimum polygon cluster and the 95% confidence ellipses formed by the morphometric data from those individuals collected at Chitande Island. The first principal component (size variable) of the morphometric data explained 96% of the observed variance, the sheared second principal component explained 25% and the third sheared principal component explained 15% of the remaining variance. Variables that had the highest loadings on the sheared second principal components of the morphometric data were preorbital depth (-0.51), distance between the posterior insertion of the anal fin and dorsal origin of the caudal fin (0.38), and the distance between the posterior insertion of the dorsal fin and the ventral origin of the caudal fin (0.27). Variables that had the highest loadings on the sheared third principal components of the morphometric data were snout length (-0.63), vertical eye diameter (0.43), and head depth (0.31). The first principal component of the meristic data explained 39.8% of the variance. Variables with the highest loadings on the first principal components of the meristic data were tooth rows on the upper jaw (0.40), pored scales posterior to the lateral line (0.36), and anal-fin rays (0.38). The HRCT scans permitted us to critically analyze the shape of the skull of the type specimens of P. livingstonii, P. elegans, and M. lanisticola, a sand-dwelling species of Metriaclima. We found that the angle that the ethmo-vomerine bloc makes with the parasphenoid is much more acute in Pseudotropheus than in Metriaclima. The angle in the holotype of P. livingstonii is 57��, and in that of P. elegans is 58��. The ethmo-vomerine bloc/ parasphenoid angle in the holotype of M. lanisticola is 48��., Published as part of Stauffer Jr, J. R., Konings, F. & Ryan, T. M., 2016, Redescription of Pseudotropheus livingstonii and Pseudotropheus elegans from Lake Mala��i, Africa, pp. 169-178 in Zootaxa 4154 (2) on pages 174-176, DOI: 10.11646/zootaxa.4154.2.4, http://zenodo.org/record/255176, {"references":["Trewavas, E. (1935) A synopsis of the cichlid fishes of Lake Nyasa. Annals and Magazine of Natural History, 10, 65 - 118. http: // dx. doi. org / 10.1080 / 00222933508655026","Stauffer, J. R. Jr., Bowers, N. J., Kellogg, K. A. & McKaye, K. R. (1997) A revision of the blue-black Pseudotropheus zebra (Teleostei: Cichlidae) complex from Lake Malawi, Africa, with a description of a new genus and ten new species. Proceedings of the Academy of Natural Sciences of Philadelphia, 148, 189 - 230.","Konings, A. F. (2007) Malawi cichlids in their natural habitat. 4 th Edition. Cichlid Press, El Paso, Texas, 424 pp."]}

Fish move in a three-dimensional environment in which it is important to discriminate between stimuli varying in colour, size, and shape. It is also advantageous to be able to recognize the same structures or individuals when presented from different angles, such as back to front or front to side. This study assessed visual discrimination abilities of rotated three-dimensional objects in eight individuals of Pseudotropheus sp. using various plastic animal models. All models were displayed in two choice experiments. After successful training, fish were presented in a range of transfer tests with objects rotated in the same plane and in space by 45° and 90° to the side or to the front. In one experiment, models were additionally rotated by 180°, i.e., shown back to front. Fish showed quick associative learning and with only one exception successfully solved and finished all experimental tasks. These results provide first evidence for form constancy in this species and in fish in general. Furthermore, Pseudotropheus seemed to be able to categorize stimuli; a range of turtle and frog models were recognized independently of colour and minor shape variations. Form constancy and categorization abilities may be important for behaviours such as foraging, recognition of predators, and conspecifics as well as for orienting within habitats or territories.

Lake Malawi is known for its endemic haplochromine species flock, most notably the rock-dwelling cichlids known as mbuna. The group of mbuna referred to as the Pseudotropheus elongatus species group is currently comprised of Metriaclima spp., Tropheops spp., Cynotilapia spp., and Pseudotropheus spp. In this study, Chindongo , a new genus with the type species C. bellicosus , is described for additional species in this group. Chindongo is distinguished from other mbuna genera by 1) the presence of bicuspid teeth in the anterior portion of the outer row of both upper and lower jaw; 2) a moderately to steeply sloped vomer with a narrow rostral tip which makes an angle of between 53° and 68° with the parasphenoid; 3) a small mouth with the lower jaw slightly shorter than the upper; 4) a broad anterior dentigerous area on both premaxilla and dentary with three or more rows of teeth (usually 5–6 rows); 5) a flank melanin pattern consisting of vertical bars without horizontal elements at any stage of development. Chindongo bellicosus is distinguished by its color pattern and shallower body from the other species which we have transferred to Chindongo . We also describe six new elongate mbuna species and place them into three available genera, they include: Metriaclima flavicauda , M. usisyae , Tropheops kumwera , T. biriwera , T. kamtambo , and Cynotilapia chilundu .

Objective: To evaluate the effect of biofloc on the growth and survival of ornamental cichlid, Blue morph. Methods/Statistical analysis: Thousand number of Blue morph were stocked in circular cement tanks of 14000 l capacity in control and biofloc rearing tanks. Various water quality parameters, qualitative and quantitative parameters of biofloc and growth parameters were estimated periodically. The results were statistically analysed using ANOVA. Results/Findings: All the water quality parameters were high in Control tank compared to biofloc. Floc volume was higher in biofloc tank (4.4 mg/l). The number of microorganisms present in biofloc was much higher than Control. The survival rate of Blue morph young ones in biofloc treatment was 93% and it was 90.2%in control.All growth parameters expect length, weight gain and mean length were significantly significant (P

A feeding trial on yellow tail cichlid Pseudotropheus acei (Regan 1922) was undertaken to asses the effect of dietary Spirulina meal as a natural carotenoid source. Four experimental diets were formulated to progressively replace 0% (C), 2.5% (SP2.5), 5% (SP5) and 10% (SP10) of fish meal weight. Ten fish per tank (initial weight 3.75 ± 0.02 g) were randomly distributed into twelve 80 l fiberglass tanks connected to a closed recirculation system (temperature 26.7 ± 0.06°C). The diets were tested in triplicate for 12 weeks. The specific growth rate of fish fed all Spirulina diets were significantly higher compared to diet C. Feed intake (FI) tended to increase with dietary Spirulina level, and fish fed diet SP10 had significantly higher FI values compared to diet C. No significant differences in feed conversion ratio were observed among these groups. Although the protein efficiency ratio of fish fed diet C was lower than that of all Spirulina diets, no significant differences were observed among these groups (P > 0.05). The total egg production and hatching rate (%) of eggs derived from all fish fed with Spirulina diets was significantly higher compared those from fish fed diet C. The yellow and blue coloration of yellow tail cichlid fed the diet containing Spirulina meal was enhanced and inclusion of dietary Spirulina meal was elevated carotenoids in skin. Results of the present study indicated that Spirulina meal has the potential to enhance the growth, reproductive performance and coloration on yellow tail cichlid.

Within the past 2 million years, the cichlids of Lake Malawi have diversified into well over 500 species resulting in one of the worlds largest lacustrine fish radiations. As a result, many of the habitats within the lake support a high diversity of species. In these highly species rich communities, male cichlids must acquire and defend a territory to successfully reproduce. Within the rock-dwelling cichlids of Lake Malawi (mbuna), this has resulted in the formation of polyspecific leks on the heterogeneous rocky benthos. Aggression is fairly common in these leks and has been tied not only to individual reproduction but to the larger phenomenon of community assembly and the maintenance of biological diversity. In this study, I examined the patterns of aggressive acts of four species within the mbuna genus Maylandia at two locations in the southern Lake Malawi. The number of aggressive acts of two sympatric species was examined at each location. At each site, one species defends territories over bedrock and the other over cobble. The number of aggressive acts across the four species was compared. The influence of habitat type on male aggression was examined and the targets of male aggression were identified to evaluate several hypotheses concerning the evolution of male aggression. The results show that aggression quantitatively varied among species, was largely directed towards heterospecifics, and was strongly influenced by habitat type. The aggressive behavior of one sympatric species pair, Maylandia benetos and Maylandia zebra, was observed under controlled laboratory conditions. Laboratory results support field observations: the bedrock associated species performed more aggressive acts and aggressive acts were directed equally at con- and heterospecifics. The results of this study suggest that habitat complexity plays a larger role in shaping aggressive behavior than other suggested factors such as competition for resources.

Courtship and agonistic interactions in an African cichlid species present a richer diversity of acoustic stimuli than previously reported. Male cichlids, including those from the genus Pseudotropheus (P.), produce low frequency short pulsed sounds during courtship. Sounds emitted by P. zebra males in the early stages of courtship (during quiver) were found to be significantly longer and with a higher number of pulses than sounds produced in later stages. During agonistic intrasexual quiver displays, males produced significantly longer sounds with more pulses than females. Also, male sounds had a shorter duration and pulse period in courtship than in male-male interactions. Taken together, these results show that the acoustic repertoire of this species is larger than what was previously known and emphasize the importance of further research exploiting the role of acoustic stimuli in intra- and interspecific communication in African cichlids.

This study describes a new courtship sound (moan) produced by Pseudotropheus spp. males, not previously reported for cichlids. Moans are short tonal sounds often showing frequency modulation. This sound type is of very low amplitude and is produced when males swim in close proximity to a female, usually before performing more exuberant behavioural exhibitions, such as darting, quivering the body and growling.

Male courtship acoustic signals from five Lake Malawi cichlid fish species of the Pseudotropheus zebra complex were recorded and compared. Sounds made by males of P. zebra, Pseudotropheus callainos and the undescribed species known as Pseudotropheus ‘zebra gold’ from Nkhata Bay, and Pseudotropheus emmiltos and Pseudotropheus faizilberi from Mphanga Rocks, differed significantly in the number of pulses and in pulse period. The largest differences in acoustic variables were found among the sympatric Mphanga Rocks species that, in contrast to the other three species, show relatively minor differences in male colour and pattern. These findings suggest that interspecific mate recognition is mediated by multimodal signals and that the mass of different sensory channels varies among sympatric species groups. This study also showed that sound peak frequency was significantly negatively correlated with male size and that sound production rate increased significantly with courtship rate.

As part of an ongoing broader investigation into whether similar morphologies among cichlid species from East African Great Lakes are due to common ancestry or convergent evolution, we used geometric morphometrics to quantitatively test the hyphothesis that Lake Tanganyika’s Tropheus spp. is morphologically similar to Lake Malawi’s Pseudotropheus spp. and Labeotropheus fuelleborni. Landmark-based techniques were used to investigate body shape variation and the results revealed highly significant differences among these genera with the exception of L. fuelleborni vs. Pseudotropheus (Tropheops) spp. An ordination of all specimens along the first two canonical variate (CV) axes indicated clear interlake separation, especially along the CV I axis, whereby Tropheus moori showed a dorsoventral expansion of the mid body section with a steeper forehead relative to Lake Malawi species. Pseudotropheus (Maylandia) zebra was discriminated from the rest primarily on the basis of its terminally positioned gape, which differed from the inferior subterminal gape that was prevalent in the other species. Thus, the present study reveals a pattern of parallel evolution between L. fuelleborni and Pseudotropheus (Tropheops) spp., but does not support an interlake convergent evolution hypothesis. Contrary to previous researchers’ assertions, these results emphasize the robustness of geometric morphometrics when testing morphological equivalence hypothesis among cichlid species. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 1–9.

Image analysis was used to measure feeding angles of Labeotropheus trewavasae, Labeotropheus fulleborni, Melanochromis auratus, Metriaclima zebra, Petrotilapia spp., Pseudotropheus c.f. elongatus, Tropheops tropheops, and Tropheops gracilior videotaped in Lake Malawi. Petrotilapia spp. fed on vertical, slanted, and horizontal slopes, T. gracilor grazed on vertical slopes approximately 60% of the time, and the other species spent at least 80% of the time feeding on horizontal slopes. The median feeding angles ranged from 35° to 90°. There are four significantly different groups of feeding angles among the eight rock-dwelling species that were examined: (1) L. trewavasae (35°), (2) L. fulleborni, M. auratus, and P. elongatus (44.8–48.5°), (3) T. tropheops (58.4°), and (4) Petrotilapia spp., T. gracilior, and M. zebra (84.2–90.2°). Feeding angles within a species did not vary with location or differences in fish community structure. Feeding angles were associated with a combination of mouth position...

One of the most compelling features of the cichlid fishes of the African Great Lakes is the seemingly endless diversity of male coloration. Colour diversification has been implicated as an important factor driving cichlid speciation. Colour has also been central to cichlid taxonomy and, thus, to our concept of species diversity. We undertook a phylogeographical examination of several allopatric populations of the Lake Malawi cichlid Pseudotropheus zebra in order to reconstruct the evolutionary history of the populations, which exhibit one of two dorsal fin colours. We present evidence that populations with red dorsal fins (RT) are not monophyletic. The RT population defining the northern limit of the distribution has evidently originated independently of the southern RT populations, which share a common ancestry. This evidence of species–level colour convergence is an important discovery in our understanding of cichlid evolution. It implies that divergence in coloration may accompany speciation, and that allopatric populations with similar coloration cannot be assumed to be conspecific. In addition to this finding, we have observed evidence for introgression, contributing to current evidence that this phenomenon may be extremely widespread. Thus, in species–level phylogenetic reconstructions, including our own, consideration must be given to the potential effects of introgression.

A new species of the cichlid genus Pseudotropheus Regan (Teleostei: Cichlidae), from Lake Malawi is described. The new species is a member of the Pseudotropheus williamsi complex from Mbenji Island. Pseudotropheus williamsi is the type species of the genus Pseudotropheus, which is a polyphyletic grouping of several species of rock-dwelling cichlids from Lake Malawi. In addition to the P. williamsi complex, Pseudotropheus contains species belonging to the P. tropheops, P. elongatus, and Pseudotropheus aggressive complexes, as well as a group of miscellaneous forms such as Pseudotropheus fainzilberi. We predict that Pseudotropheus eventually will be restricted taxonomically to include only members of the P. williamsi complex, but because of the lack of phylogenetic data on many of the miscellaneous forms (e.g., P. fainzilberi) we are currently unable to diagnose Pseudotropheus as monophyletic.

Gravid female Malawian Pseudotropheus cichlids spent significantly more time with males that they subsequently chose as mates, indicating that time spent near a male is a valid and accurate method of measuring female preference. Furthermore, females preferred to mate with males that had longer pelvic fins and a larger number of eggspots on their anal fins. In some instances, females chose to mate with both of the males with which they were presented, possibly because they were unable to discriminate between them.

Nine polymorphic microsatellites were isolated from a genomic DNA library of Oreochromis mossambicus enriched with di- and tetranucleotide repeats. The three di- and six tetranucleotide-type markers were characterized in 40 Mozambique tilapia individuals collected from a local farm. The number of alleles at the nine microsatellite loci ranged from 3 to 31, with an average of 13.4/locus. The average expected heterozygosity was 0.79 (range: 0.65–0.94), whereas the average observed heterozygosity was 0.67 (range: 0.33–1). Three loci significantly deviated from Hardy–Weinberg equilibrium, presumably due to limited population size. Cross-species amplification was successful for seven markers in Oreochromis niloticus, a phylogenetically closely related species and for six markers in Pseudotropheus lombardi, an ornamental cichlid for which no microsatellites have been described to date. These markers could provide important tools for the determination of genetic diversity and population structure of O. mossambicus.

Little is known about mate recognition systems among the species-rich cichlid flocks of the African Great Lakes. Such knowledge is critical to our understanding of how evolutionary processes have brought about the current diversity. In the present study we focused on three anatomically similar species of rocky shore cichlid fish Pseudotropheus (Maylandia) spp. from Lake Malawi. We scored male responses to heterospecific and conspecific females which were enclosed in separate watertight transparent chambers. Any male behaviour we observed was therefore due to visual cues alone. Although males of some species could clearly identify conspecific females on visual cues alone, others could not. In cases where conspecific and heterospecific females were phenotypically similar, males could not consistently distinguish between them. Further experiments are required, however, to see whether males can recognize these females using alternative means, such as olfactory cues. Copyright 1999 The Association for the Study of Animal Behaviour.

1. The rocky habitat communities of Lake Malawi contain a high diversity of ecologically similar, predominantly herbivorous, cichlid fish species. How so many species can coexist is still unknown. 2. Adult males of the majority of these species hold permanent territories which form dense multispecies mosaics across the shores. 3. The study examined six coexisting species of cichlids from the rocky habitat where males are known to control access to the algal food resources within their territorial space. These included four sibling species of the Pseudotropheus (Tropheops) species complex, which are specialized epilithic algal herbivores, and two sibling species of the trophically more generalist P. (Maylandia) species complex which feed upon both epilithic algae and plankton. 4. The hypotheses that both intraspecific and interspecific territoriality occur in these communities and that interspecific aggression initiated by territorial males is preferentially directed at species with the most similar diets to their own were tested. 5. It was found that males preferred to exclude conspecific intruders, while they tolerated intruders with different diets to their own. Also, male P. (Tropheops) preferentially excluded similar heterospecific dietary specialists, while male P. (Maylandia) tolerated similar heterospecific dietary generalists. 6. Based on this study, it is proposed that interspecific territoriality may be reducing competition between species with different diets and promoting their coexistence, while it may be enhancing competition between species with the same diet. Furthermore, it suggests that ecological generalism may be reducing the intensity of interspecific competition, while specializations for the same resources may be increasing competition.

The condition factor and fecundity of the translocated rock-dwelling cichlid fish, Cynotilapia afra, Pseudotropheus callainos, and Pseudotropheus tropheops‘red cheek’ at Thumbi West Island, southern Lake Malawi, were compared with those at their sites of origin, in the north of the lake. The guiding hypothesis was that these species, having originated from a region of the lake which is generally poor in nutrients, and been introduced to an area richer in nutrients, would be in better condition and more fecund there than at their sites of origin. That seemed to be the case. P. callainos and P. tropheops‘red cheek’ had significantly higher condition factors and fecundity indices at Thumbi West Island than at their sites of origin. However, both condition factor and fecundity of all the species studied fluctuated seasonally. The major peaks in condition factor coincided with either the wind-induced lake upwelling from June to August, or the rains. Major peaks in fecundity occurred at the end of the rainy season, between February and April, or at the end of the upwelling period between September and October. The translocated species began to breed at a smaller size at their sites of origin in the north than at Thumbi West Island, probably as an adaptive response to a poor nutrient regime in the north. The increase in population of some translocated species can be partly attributed to their improved condition and fecundity due to enhanced nutrient availability at the site where they have been introduced. This may have negative implications for the native taxa, more particularly as competition for breeding space is rife among the rock-dwelling cichlids of Lake Malawi.

The Lake Malaŵi genus Melanochromis included five species at its inception and was originally distinguished from Pseudotropheus on the basis of morphology, including the arrangement of teeth on the lower pharyngeal bone. Thediagnosis has been extended twice, first to include all elongate mbuna that possess horizontal stripes and U-shaped toothbands and later to exclude mbuna that do not exhibit a sex-related reversal in their colour pattern. Recently, the diagnosisof the genus was refined on the basis of the melanin pattern. The genus now includes only species with a basic melaninpattern, which consists of two black horizontal lateral stripes on a light background. Most adult members of the genus,thus defined, have a sex-related reversal of pigmentation pattern. Here we describe Melanochromis mpoto n. sp. from thenorthwestern part of Lake Malawi, synonymize M. parallelus Burgess & Axelrod 1976 with M. loriae Johnson 1975,redescribe M. chipokae Johnson 1975 and M. robustus Johnson 1985, and reclassify and designate a lectotype for M. brevis Trewavas, 1935.

The ontogenesis and involution of thymus in cichlid fishes was studied with the aim of comparing development in the bottom-spawning species Tilapia zillii and T. tholloni, and in the mouth-brooding species Oreochromis auratus, O. niloticus, O. mossambicus, and Sarotherodon galilaeus. For comparison, data are also given on bottom-spawning Cichlasoma spp. from America and mouth-brooding Pseudotropheus auratus and Aulonocara nyassae from Africa. Developmental changes were followed histologically by means of light and electron microscopy of sections, beginning with embryos 24 h after fertilization, up to 14-year-old specimens of O. auratus. In all these fish, the anlagen of the thymus glands begins from the third and fourth gill pouches, and their development shows a high correlation with the pace of general organogenesis, which differs greatly in the bottom-spawning and mouth-brooding cichlids. In juveniles of bottom-spawners of 20-40 mm total length and in mouth-brooders of 40-60 mm total length, three cell types are present in the thymus: thymocytes, with large, dense nuclei; epitheliocytes, with long cell extensions containing bundles of tonofibrils; and reticulocytes, with short, granulated cell extensions. Hassall's corpuscles start to develop in larvae of T. zillii at 20-35 mm total length, and in specimens of 40 mm and more total length the corpuscles are typical, formed by inner and outer rings of epitheliocytes. At 30-45 mm total length, cell debris starts to accumulate in the interior of the corpuscles as an early sign of regression. As involution continues, macrophages accummulate within and around the Hassall's corpuscles. The epitheliocyte rings are eventually completely broken down. Isles of thymocytes persist in tilapias from the age of 1-14 years, but most of the thymus volume is occupied by blood lacunae and pigmented macrophage aggregations. The morphology is similar in the mouth-brooding species Pseudotropheus beginning at 1.5 years of age. © 1995 Wiley-Liss, Inc.

The rational design of closed aquaculture systems requires data on metabolite production rates. The metabolite of primary concern is often ammonia. Ammonia formation rates for a number of tropical ornamental fish types and sizes were determined. Cyprinus carpio, Barbus conchonius, Pseudotropheus auratus and Carassius auratus auratus were used as representative egg-layers while Xiphophorus variatus and Xiphophorus helleri represented the live-bearers. Specific metabolite production rates, R′, were determined not only in terms of mass of fish but also the amount of feed. For instance, R′ (Amm-N) for 1.33 g unit size Barbus conchonius was determined to be 155.9 mg Amm-N kg-fish−1% feed−1 day−1. In an attempt to produce a general model for all the ornamental fish investigated, all values of R′ obtained were correlated with fish sizes to produce an equation R′ (Amm-N) = 1.57-[30×log(itUW)] where UW = unit fish size.

It has been suggested that speciation on the basis of sexual selection is an important mechanism for the generation of new species for East African cichlids, where male body coloration is one of the major discriminatory factors used by females in mate choice. To gain insight into the molecular basis of cichlid coloration, we studied the Lake Malawi cichlid Pseudotropheus saulosi, comparing transcription in the bright blue skin of males to the yellow skin of females. Our cDNA microarray experiments identified 46 clones that exhibited expression differences between the two sexes, of which five were confirmed to be differentially expressed by relative quantitative real-time PCR (qRT-PCR). This gene list includes a representative from the endosomal-to-Golgi vesicle trafficking pathway, Coatomer protein complex, subunit zeta-1 (Copz-1), which is known to be a critical determinant of pigmentation in humans and zebrafish. With the support of microscopic images of the skin of these specimens, we interpret the transcriptional differences between the blue males and yellow females. Here, we provide insight into the putative functional diversification of genes involved in the coloration of cichlids and by extension, on the evolution of coloration in teleost fish.

Multiple cues, across multiple sensory modalities, are involved in mate choice in a wide range of animal taxa. This multiplicity leads to the prediction that, in adaptive radiations, sexual isolation results from divergence in multiple dimensions. However, difficulties in directly measuring preferences and detecting multiple effects limit our ability to empirically assess the number of independent traits contributing to mate choice and sexual isolation. We present an approach to estimate the dimensionality of sexual isolation using mating trials across groups of related populations. We analyze nine radiations: seven in fruit flies ( Drosophila ) and one each in salamanders ( Desmognathus ) and cichlid fishes ( Pseudotropheus ). We find strong evidence that multiple latent traits—linear combinations of phenotypic traits and preferences—are responsible for the patterns of sexual isolation in all nine radiations but that dimensionality has a strong upper limit. Just two latent traits are implicated in the majority of cases. Mapping along latent trait axes tests predictions of sexual-selection models and allows correlation with specific phenotypic traits and functional components of mate choice. We find support for the role of stabilizing natural selection on the sexually selected (male) traits. In the cichlids, latent-trait axes incorporate male-coloration patterns and exhibit convergence as well as divergence among populations. In the salamanders, temporal patterning in sensory modalities and male vs. female preferences are reflected in different latent-trait axes.

Major environmental events that fragment populations among multiple island habitats have potential to drive large-scale episodes of speciation and adaptive radiation. A recent palaeolimnological study of sediment cores indicated that Lake Malawi underwent major climate-driven desiccation events 75 000‐135 000 years ago that lowered the water level to at least 580 m below the present state and severely reduced surface area. After this period, lake levels rose and stabilized, creating multiple discontinuous littoral rocky habitats. Here, we present evidence supporting the hypothesis that establishment and expansion of isolated philopatric rock cichlid populations occurred after this rise and stabilization of lake level. We studied the Pseudotropheus (Maylandia) species complex, a group with both allopatric and sympatric populations that differ in male nuptial colour traits and tend to mate assortatively. Using coalescent analyses based on mitochondrial DNA, we found evidence that populations throughout the lake started to expand and accumulate genetic diversity after the lake level rise. Moreover, most haplotypes were geographically restricted, and the greatest genetic similarities were typically among sympatric or neighbouring populations. This is indicative of limited dispersal and establishment of assortative mating among populations following the lake level rise. Together, this evidence is compatible with a single large-scale environmental event being central to evolution of spatial patterns of genetic and species diversity in P. (Maylandia) and perhaps other Lake Malawi rock cichlids. Equivalent climate-driven pulses of habitat formation and fragmentation may similarly have contributed to observed rapid and punctuated cladogenesis in other adaptive radiations.

Mate preferences on male colour have been implicated in generating and maintaining species diversity among haplochromine cichlid fish. Their lek-like mating system suggests that not only male colour but also territory quality is instrumental inmate choice. We assessed the relative importance of territory quality and male colour in mate choice by testing whether territory quality can override the female preference for males of her own colour in the Lake Victoria cichlid genus Pundamilia. First, we showed in experimental groups that the dominant male preferentially monopolised a large tube relative to a small tube. The situation mimics quality difference in rocky crevices that serves as a focal point for male courtship display. Second, in mate-choice tests, Pundamilia nyererei females were allowed to choose between closely related P. nyererei and P. pundamilia males; these species differ strikingly in male nuptial coloration, but little else. We gave either both males the same small tube or one of them a large tube. The preference of P. nyererei females for P. nyererei males in the control situation (where both males had a small tube) was significantly diminished in favour of P. pundamilia males when the latter had the large tube. The results provide experimental evidence that differences in territory quality can override the female preference for males of her own colour. This finding is critical for a recent hypothesis proposing that male competition for mating territories can facilitate the process of sympatric speciation by sexual selection.

Territoriality fundamentally influences animal mating systems and patterns of population structure. Although territory ownership is already known to contribute importantly to male reproductive success and the ecological coexistence of African rock-dwelling cichlids, the significance of variation in territory features has received little attention in these fishes. In Lake Malawi, males of Pseudotropheus tropheops “orange chest” defend territories on either of two substrate classes at Harbour Island: flat rock slabs lacking crevices and caves, or structurally complex boulder fields containing cave shelters. Focal watches of this species demonstrated that both territory size and occupancy on either substrate type depend on the size of male residents. Males larger than a threshold size exclusively held the largest and most structurally complex territories. After removal of conspecific residents, more vacant territorial areas on cave-containing substrate were reoccupied by “orange chest” males in full breeding coloration compared to vacant areas on flat substrate. These findings suggest competition among “orange chest” males for complex rocky substrate. Defense of caves was associated with enhanced male courtship rates: the number of caves within a male’s territory was a better predictor of courtship activity than was male size or territory area. In addition to territories being crucial for male reproductive success and therefore likely playing a role in sexual selection, male–male competition for caves in rock-dwelling cichlids may be promoted by the ecological advantage of enemy-free space. Smaller “orange chest” males lacking caves tended to move into adjacent boulder fields in the presence of predators, particularly at night. In contrast, males defending caves were more likely to remain on their territories when nocturnal predators were present. The territorial behaviors of P. tropheops “orange chest” that we observed in situ provide an instructive natural framework for testing the roles of substrate and ecology in the mating systems of rock-dwelling cichlid fishes.

It has been suggested that sympatric speciation can be driven by sexual selection on male mating traits alone. However, a fundamental problem for this process is the lack of ecological differentiation that would stabilize the coexistence of incipient species through frequency-dependent selection. Such selection can also occur if male aggression is primarily directed towards similar rather than towards dissimilar phenotypes, so that rare male phenotypes would enjoy a negatively frequency-dependent fitness advantage. We experimentally tested such an aggression bias in two recently diverged, ecologically and anatomically similar sympatric cichlid species pairs of the genus Pundamilia from Lake Victoria. Territorial males of a pair of partially reproductively isolated species with red and blue nuptial coloration, respectively, studied in the laboratory were confronted simultaneously with both colour types enclosed in transparent tubes. Red males were more aggressive to red stimuli under white light but not when colour differences were masked under green light. Blue males were equally aggressive to both stimuli in both light conditions. Males of two apparently fully reproductively isolated species, again one with red and one with blue nuptial coloration, studied in the field, both directed more aggressive behaviour towards conspecific than towards heterospecific stimulus males. The differential allocation of aggression would create an advantage for males of the less abundant phenotype or species, thereby potentially supporting stable coexistence of the phenotypes. The finding that this effect was less clear in the partially reproductively isolated species pair than in the fully isolated species pair is discussed.

Research on reproductive isolation in African cichlid fishes has largely focused on the role of nuptial colours, but other sensory modes may play an important role in mate choice. Here, we compare the relative importance of visual and olfactory cues in mate recognition by females of a Lake Malawi cichlid species. Female Pseudotropheus emmiltos were given a choice of spawning next to a conspecific male or a male of the closely-related sympatric Pseudotropheus fainzilberi . Significant preference for conspecific males only occurred when olfactory cues were present. This suggests that divergence of olfactory signals may have been an important influence on the explosive radiation of the East African species flock.

Courtship sounds made by three sympatric cichlid species, Pseudotropheus zebra, P. callainos and an undescribed species known as P. 'zebra gold' were recorded and compared to investigate the potential role of acoustic signals in mate choice. Sounds were emitted during 'quiver' and 'circle' components of the male courtship display and consisted of rapidly repeated pulse units. Some sound variables differed significantly among species with P. callainos generally being separated from the other two species. This species produced sounds with higher peak frequency (for a given length) and lower number of pulses than P. 'zebra gold' and higher pulse durations than P. zebra. In addition, standard length was inversely related to peak frequency in both P. 'zebra gold' and P. callainos (this relation was not tested in P. zebra due to the small sample size). These differences might indicate different regimes of intraspecific sexual selection among the three species.

To test the hypothesis of parallel speciation by sexual selection, we examined length variation at six microsatellite loci of samples from four sites of four to six putative species belonging to two subgenera of rocky shore mbuna cichlids from Lake Malawi. Almost all fixation indices were significantly different from zero, suggesting that there is presently little or no gene flow among allopatric populations or sympatric species. Analysis of variance indicated that genetic distances among allopatric populations of putative conspecifics were significantly lower than among sympatric populations of heterospecifics. The topology of trees based on distance matrices was also largely consistent with the hypothesis that the putative species are monophyletic and have thus not evolved in parallel in their present locations. If parallel speciation does occur in Malawi cichlids, it may be on a larger spatial scale than investigated in our study.

Recent studies have suggested that size homoplasy is a prevalent feature of microsatellites and is expected to increase with time of divergence among populations and taxa. In this study, we performed sequence analysis of alleles from a complex microsatellite locus (Pzeb4, initially isolated from Pseudotropheus (Maylandia) zebra) from 1 midwater-feeding and 10 rock-dwelling cichlid fish species from Lake Malawi, East Africa, to investigate how widespread size homoplasy is among closely related taxa at this locus. All cichlid fishes endemic to this lake are believed to have originated within the last 700,000 years, and some species may be less than 200 years old. The number of eletromorphs found per species varied from 3 to 13. Sequence analysis of 95 cloned Pzeb4 PCR products (representing 18 electromorphs) revealed 13 new alleles. Ten of the 13 electromorphs (77%) were found to show size homoplasy due to either single nucleotide substitutions/indels or large indels. To investigate how well this locus fits the single-step mutation model (SMM), the minimum number of mutations required to explain the length differences between pairs of alleles was plotted against their size differences. Of the 300 comparisons, 166 (55.3%) corresponded to SMM expectations and 86 (28.7%) required a smaller number of mutations, and for 48 (16.0%) pairwise comparisons, a larger number of mutations were required to explain the length differences as compared with SMM expectations. Finally, a large deletion in the microsatellite sequence observed in the three rock-dwelling species Pseudotropheus lucerna, Pseudotropheus (Tropheops) 'band,' and Pseudotropheus (Tropheops) 'rust' and the midwater-feeding species Copadichromis sp. is believed to represent a shared ancestral polymorphism.

The gross morphology of cichlid digestive tracts is investigated in 71 African, Neotropical and Asian species with differing food preferences and body shapes. Eight other perciform families are included for outgroup comparison. The ontogeny of the digestive tract is investigated in four cichlid species. The arrangement of the digestive tract of cichlids is unique among all fishes examined hitherto: the stomach's extendible blind pouch, the left hand exit to the anterior intestine and the first intestinal loop at the left side. This corroborates the monophyly of the family. The length of cichlid intestines and their concomitant coiling types appear to depend upon food preference: piscivorous, paedophagous and crustacean eating species have simple and short intestines, whilst phytophagous, insectivorous, detritivorous, zoo- and phytoplanktivorous forms are characterized by long intestines. The intestinal length of the different molluscivorous species examined depends on the amount of detritus in the diet. The possible adaptive significance of intestinal lengthening is discussed and three different ways of intestinal arrangement are defined. The digestive tracts of the African genera Haplochromis, Hoplotilapia, Platytaeniodus, Astatoreochromis, Macropleurodus, Pseudotropheus, Melanochromis, Cyrtocara, Petrotilapia, Au lonocara, Labeotropheus, Pelvicachromis and Sarotherodon are characterized by a typical dorsal intestinal flap-back-loop. This loop is lacking in the west African genus Hemi chromis, in all Neotropical cichlids and in all outgroup taxa examined and as such appears to be of possible phyletic significance.

Three sympatric sibling species of Petrotilapia, with similar dietary and macrohabitat requirements, occur near Monkey Bay, Lake Malawi. Males and females of all three species fed selectively on the rocky shores. Males utilized less than 6% of the space they defended as a breeding territory for feeding and although interspecific overlap of territories was considerable, only 2.5% of the feeding space used by territorial males was shared. Males primarily utilized rich food patches which occurred within the territories of highly aggressive Pseudotropheus species, whereas females tended to feed in undefended areas. Although Petrotilapia species are not highly aggressive fishes, there was a well-defined social dominance hierarchy amongst them and it is suggested that feeding-site utilization is dependent on social rank. Inter-and intraspecific differences in feeding-site utilization probably facilitate species coexistence and thus contribute to the maintenance of the high species diversity which is a characteristic of the ichthyofauna of Lake Malawi.

Tilapia rendalli of Lake Malawi dig large tunnels in their nests and practise communal care of young. Both these traits are considered to be antipredator adaptations.

The Lake Malaŵi genus Melanochromis included five species at its inception and was originally distinguished from Pseudotropheus on the basis of morphology including the arrangement of pharyngeal teeth. The diagnosis has been extended twice, first to include all elongate mbuna that possess horizontal stripes and U-shaped tooth bands and later to exclude mbuna that do not exhibit a sex-related reversal in their color pattern. We have further refined the diagnosis of the genus on the basis of the melanin pattern, resolved a longstanding dispute regarding the validity of M. heterochromis, re-evaluated the status of M. vermivorus, synonymized M. mellitus Johnson 1976 with M. melanopterus Trewavas 1935, moved M. benetos Bowers and Stauffer 1977 to Pseudotropheus, and described M. kaskazini, M. wochepa, and M. mossambiquensis from the eastern shore of the lake. Melanochromis is still paraphyletic as two species, M. joanjohnsonae Johnson 1974 and M. labrosus Trewavas 1935, are not congruent with the rest of the group, but, currently, a better alternative for these two could not be found.

A 12-week growth trial was conducted to determine the effects of dietary protein on the growth of the yellow tail cichlid, Pseudotropheus acei, and on water quality in closed recirculating systems. Six test diets were formulated to contain protein levels ranging 25-50% by substituting corn oil and α-starch for fishmeal. Diets were assigned to triplicate groups of 10 fish in a completely randomized design. The feed conversion ratios of fish fed the 35% and 50% crude protein diets were significantly (p