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The ornamental fish industry has continued to flourish since eighteenth century with increased fascination by enthusiasts in the striking body colours and patterns displayed in the fishes, a beneficial outcome of rigorous selective programmes. The expression of these pigmented colours is the result of the differentiation and orientation of specialised chromatophores located within the dermal layer. The different types of chromatophores found in many ornamental fish species, are the basis of the unique colour hues and patterns. This review discusses the current approaches for enhancing the body pigmentation and pattern of ornamental fishes. Two factors are considered to be the main drivers of body colour regulation: feed additives (pigments) and rearing environment setup, i.e. tank colour and light. Potential candidate pigment genes to manipulate the ornamental fish body pigmentation and pattern have been elucidated through mapping of putative regulatory pathways, buoyed by the rapid development of next generation sequencing technologies. The effects of feed additives, tank background colour and light on various ornamental fish species, and regulatory pathways of involved genes offer valuable insights for enhanced variety production prior to genetic engineering and are herein discussed. It is hoped that the systematic analysis of the current knowledge in this review would be a boon for the ornamental fish community to step up efforts to boost the ornamental fish breeding industry. [ABSTRACT FROM AUTHOR]

The feasibility of culturing different blue Haslea species and strains in different types of photobioreactors (PBRs) was studied on the long-term (until 151 days). The different strains of blue Haslea were selected for their peculiarity to produce marennine-like blue pigments as a potential industrial high-value compound. The present study aims at assessing several factors in PBRs to obtain sustained blue pigment production in semi-continuous culture. Therefore, the effect of mixing, silicate concentration in the culture medium and type of light on marennine or marennine-like pigment production were investigated in parallel to the productivity of different Haslea strains and species. It was shown that the presence of mixing in semi-continuous PBR affected marennine production, cultures without any mixing achieving significantly higher marennine concentrations and productivities. Additionally, concentrations of silica from 45 to 75 μg L−1 in the culture medium produced higher marennine concentrations than that of 30 μg L−1. There were no significant differences in marennine production between the LEDs mixing different color and fluorescent tubes in semi-continuous PBR, thus LED could be a great option from the sustainability standpoint. Marennine production in the standard conditions used for this work was largely different between species. Haslea sp. produced the lowest pigment yields comparatively to the three H. ostrearia strains showing similar marennine productivity over 14 mg L−1. Preservation, until 155 days of marennine separated from culture supernatant and concentrated ("blue water") was increased at low temperature (4 °C) and absence of light. This study validates the efficiency of semi-continuous systems to support long-term marennine production. However, additional work is still needed to pinpoint other factors that can further reduce the costs and result in maximum yields of marennine for industrial applications. • The marine diatom genus Haslea produces the marennine (MP) and marennine-like blue pigment (MLP). • To increase productivity of MP and MLP, conditions need to be optimized for long term production. • Mixing, concentration of silica, and strain origin significantly affect marennine production. • Light from LED could be a great option in marennine production from the sustainability standpoint. • Methods of preservation affect degradation of marennine. [ABSTRACT FROM AUTHOR]

Using light, scanning and transmission electron microscopy, and SSU rDNA and rbcL gene sequencing, we investigated three marine benthic diatoms: Haslea avium Tiffany, Herwig et Sterrenburg; H. feriarum Tiffany et Sterrenburg and H. tsukamotoi Sterrenburg et Hinz collected from intertidal sediments in China. These are the first records of these three species from China. Our observations showed that the typical valve structure of Haslea, with an inner basal layer and an outer tegumental layer, and walls (saepes sensu Sterrenburg et al.) between them is not present in either H. tsukamotoi or H. avium. Moreover, the two species possess small helictoglossae, an internal apical thickened area and hooked terminal fissures reaching to the valve mantle, suggesting a close relationship with Navicula tripunctata, the type species of Navicula s.s. In molecular phylogenetic analyses, Haslea was polyphyletic, being divided into two separate clades: H. feriarum belonged to a clade that comprised only Haslea species, including the type H. ostrearia, while H. tsukamotoi and H. avium were within the Navicula clade. Therefore, we propose transferring H. tsukamotoi and H. avium to Navicula and suggest that the presence of continuous longitudinal strips on the external valve surface is not a synapomorphy, but rather a homoplastic character for Haslea. [ABSTRACT FROM AUTHOR]