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Accurately measuring the phenotype at the individual level is critical to the success of selective breeding programs. Feed efficiency is a key sustainability trait and is typically approached through feed conversion ratio (FCR). This requires measurements of body weight gain (BWG) and feed intake (FI), the latter being technically challenging in fish. We assessed two of the principal methods for measuring feed intake in fish over consecutive days: (1) group rearing 10 fish per group and video recording the meals and (2) rearing fish individually on a restricted ration. Juvenile Nile tilapia (Oreochromis niloticus) from the Genetically Improved Farmed Tilapia (GIFT) strain and the Cirad strain were entered into the study (128 GIFT and 109 Cirad). The GIFT strain were reared over three consecutive periods of 7 days each under different feeding, recording, and rearing scenarios (i) in groups fed an optimal ration (g100) or (ii) fed a 50% restricted ration (g50) both with video records of all meals and (iii) reared in isolation and fed a 50% restrictive ration. The Cirad strain were tested similarly but only for scenarios (i) and (iii). All fish were fed twice daily with a calculated ration. Correlations showed the same trends for the GIFT and the Cirad strains. For the GIFT strain, correlations were positive and significant for BWG and FI measured in scenarios (i) and (ii), 0.49 and 0.63, respectively, and FI measured in scenarios (i) and (iii) (0.50) but not for BWG measured in scenarios (i) and (iii) (0.29, NS). The phenotypic correlation estimated for FCR between scenarios (i) and (ii) with fish fed an optimal or a 50% restricted ration was low and not significant (0.22). Feed Conversion Ratio for GIFT fish reared in groups or in isolation and fed with a restricted ration [scenarios (ii) and (iii)] were not significantly correlated either. Social interactions between fish, potentially impacting their efficiency, may explain the results. Therefore, selective breeding

Accurately measuring the phenotype at the individual level is critical to the success of selective breeding programs. Feed efficiency is a key sustainability trait and is typically approached through feed conversion ratio (FCR). This requires measurements of body weight gain (BWG) and feed intake (FI), the latter being technically challenging in fish. We assessed two of the principal methods for measuring feed intake in fish over consecutive days: (1) group rearing 10 fish per group and video recording the meals and (2) rearing fish individually on a restricted ration. Juvenile Nile tilapia (Oreochromis niloticus) from the Genetically Improved Farmed Tilapia (GIFT) strain and the Cirad strain were entered into the study (128 GIFT and 109 Cirad). The GIFT strain were reared over three consecutive periods of 7 days each under different feeding, recording, and rearing scenarios (i) in groups fed an optimal ration (g100) or (ii) fed a 50% restricted ration (g50) both with video records of all meals and (iii) reared in isolation and fed a 50% restrictive ration. The Cirad strain were tested similarly but only for scenarios (i) and (iii). All fish were fed twice daily with a calculated ration. Correlations showed the same trends for the GIFT and the Cirad strains. For the GIFT strain, correlations were positive and significant for BWG and FI measured in scenarios (i) and (ii), 0.49 and 0.63, respectively, and FI measured in scenarios (i) and (iii) (0.50) but not for BWG measured in scenarios (i) and (iii) (0.29, NS). The phenotypic correlation estimated for FCR between scenarios (i) and (ii) with fish fed an optimal or a 50% restricted ration was low and not significant (0.22). Feed Conversion Ratio for GIFT fish reared in groups or in isolation and fed with a restricted ration [scenarios (ii) and (iii)] were not significantly correlated either. Social interactions between fish, potentially impacting their efficiency, may explain the results. Therefore, selective breeding

Accurately measuring the phenotype at the individual level is critical to the success of selective breeding programs. Feed efficiency is a key sustainability trait and is typically approached through feed conversion ratio (FCR). This requires measurements of body weight gain (BWG) and feed intake (FI), the latter being technically challenging in fish. We assessed two of the principal methods for measuring feed intake in fish over consecutive days: (1) group rearing 10 fish per group and video recording the meals and (2) rearing fish individually on a restricted ration. Juvenile Nile tilapia (Oreochromis niloticus) from the Genetically Improved Farmed Tilapia (GIFT) strain and the Cirad strain were entered into the study (128 GIFT and 109 Cirad). The GIFT strain were reared over three consecutive periods of 7 days each under different feeding, recording, and rearing scenarios (i) in groups fed an optimal ration (g100) or (ii) fed a 50% restricted ration (g50) both with video records of all meals and (iii) reared in isolation and fed a 50% restrictive ration. The Cirad strain were tested similarly but only for scenarios (i) and (iii). All fish were fed twice daily with a calculated ration. Correlations showed the same trends for the GIFT and the Cirad strains. For the GIFT strain, correlations were positive and significant for BWG and FI measured in scenarios (i) and (ii), 0.49 and 0.63, respectively, and FI measured in scenarios (i) and (iii) (0.50) but not for BWG measured in scenarios (i) and (iii) (0.29, NS). The phenotypic correlation estimated for FCR between scenarios (i) and (ii) with fish fed an optimal or a 50% restricted ration was low and not significant (0.22). Feed Conversion Ratio for GIFT fish reared in groups or in isolation and fed with a restricted ration [scenarios (ii) and (iii)] were not significantly correlated either. Social interactions between fish, potentially impacting their efficiency, may explain the results. Therefore, selective breeding

The present study aimed to develop nondestructive methods to accurately follow the growth of fish larvae and post-larvae. European sea bass (Dicentrarchus labrax) aged 71-100 days post fertilization (dpf; 20-419 mg) and Nile tilapia (Oreochromis niloticus) aged 14 dpf (10-25 mg) were used as model species. Several measurements were performed on digital pictures of larvae to model body weight. Using body surface area, contour, length and depth, it was possible to estimate accurately the body weight of young European sea bass and Nile tilapia (r² of 0.98 and 0.95, respectively).

The present study aimed to develop nondestructive methods to accurately follow the growth of fish larvae and post-larvae. European sea bass (Dicentrarchus labrax) aged 71-100 days post fertilization (dpf; 20-419 mg) and Nile tilapia (Oreochromis niloticus) aged 14 dpf (10-25 mg) were used as model species. Several measurements were performed on digital pictures of larvae to model body weight. Using body surface area, contour, length and depth, it was possible to estimate accurately the body weight of young European sea bass and Nile tilapia (r² of 0.98 and 0.95, respectively).

The present study aimed to develop nondestructive methods to accurately follow the growth of fish larvae and post-larvae. European sea bass (Dicentrarchus labrax) aged 71-100 days post fertilization (dpf; 20-419 mg) and Nile tilapia (Oreochromis niloticus) aged 14 dpf (10-25 mg) were used as model species. Several measurements were performed on digital pictures of larvae to model body weight. Using body surface area, contour, length and depth, it was possible to estimate accurately the body weight of young European sea bass and Nile tilapia (r² of 0.98 and 0.95, respectively).

The present study aimed to develop nondestructive methods to accurately follow the growth of fish larvae and post-larvae. European sea bass (Dicentrarchus labrax) aged 71-100 days post fertilization (dpf; 20-419 mg) and Nile tilapia (Oreochromis niloticus) aged 14 dpf (10-25 mg) were used as model species. Several measurements were performed on digital pictures of larvae to model body weight. Using body surface area, contour, length and depth, it was possible to estimate accurately the body weight of young European sea bass and Nile tilapia (r² of 0.98 and 0.95, respectively).

Behaviour and social factors are important for the reproduction of O. niloticus. The influence of social interactions on the fry production was analyzed using a domestic strain. In a first step (S1), females with high and low reproductive potential (HRP and LRP) were detected within a group of breeders. Two groups (G1 and G2) were constituted with a sex ratio of 3 males / 7 females (1:2.3). G1 presented a significant difference in the average spawning rate of HRP and LRP females (3.5 ± 0.58 and 0.33 + 0.58 spawns.female-1 respectively). We then carried out social reorganizations based on the previously established (SI) reproductive potential (RP). Two groups (GA and GB) with FRP (sex ratio: 1:3) and HRP females (sex ratio: 1:4) respectively were constituted using the G1 breeders. These social reorganizations have strongly affected individual RP and the dominance (aggressiveness) of some LRP females. Within GB, the average spawning number decreased from 3.5 ± 0.58 to 0.75 ± 0.96 spawns.female-1. These results suggest a strong influence of behavioural and social components in the RP of breeders. Interestingly, some HRP females retain their high RP following a social reorganization.

Behaviour and social factors are important for the reproduction of O. niloticus. The influence of social interactions on the fry production was analyzed using a domestic strain. In a first step (S1), females with high and low reproductive potential (HRP and LRP) were detected within a group of breeders. Two groups (G1 and G2) were constituted with a sex ratio of 3 males / 7 females (1:2.3). G1 presented a significant difference in the average spawning rate of HRP and LRP females (3.5 ± 0.58 and 0.33 + 0.58 spawns.female-1 respectively). We then carried out social reorganizations based on the previously established (SI) reproductive potential (RP). Two groups (GA and GB) with FRP (sex ratio: 1:3) and HRP females (sex ratio: 1:4) respectively were constituted using the G1 breeders. These social reorganizations have strongly affected individual RP and the dominance (aggressiveness) of some LRP females. Within GB, the average spawning number decreased from 3.5 ± 0.58 to 0.75 ± 0.96 spawns.female-1. These results suggest a strong influence of behavioural and social components in the RP of breeders. Interestingly, some HRP females retain their high RP following a social reorganization.