Erratum to: Effect of dietary high amount of calcium and phosphorus on reducing the prevalence of morphological deformities in GH-transgenic Nile tilapia

To satisfy the world’s growing need for animal protein, it is important to develop or select fish species which are suitable for optimal cultivation in closed recirculating aquaculture systems (CRASs) as an environment-friendly aquaculture technology for providing safe and secure aquaculture food products. We have developed an ‘all fish’ growth-hormone (GH)-transgenic Nile tilapia Oreochromis niloticus (GHTi) which appears to be a predominant candidate for CRAS since it has been found to exhibit two important characteristics, namely, a shorter rearing duration to a market size and lowered N and P discharge load. However, these fish have undergone morphological changes, resulting in a short body which is less acceptable to consumers as an edible fish. One possible solution to reducing the prevalence of such morphological deformities is to determine the association between changes in the nutritional conditions of these fish. To this end, we first calculated the ideal total calcium (Ca) and phosphorous (P) intake (g/kg), ideal daily Ca and P intake and retention (g/kg/day) and ideal daily feeding rate (%) for the fourth filial (F4) offspring of GHTi. Our hypothesis was that GHTi would achieve the same total retention of Ca (14.6 g/kg) or P (7.69 g/kg) during a 69-day shorter rearing period as their production-matched pedigree common domestic strain (CTi). We estimated that when GHTi were fed conventional commercial diets to satiety, those with a body weight (BW) of more than approximately 230 g could not retain sufficient Ca, while those with a BW of more than approximately 429 g could not retain sufficient P. We then attempted to reduce the prevalence of morphological deformities in GHTi via dietary compound regulation by supplying a high amount of dietary Ca [6.82 % in the diet with Ca supplementation (Ca-S)] or P [4.75 % in the diet with P supplementation (P-S)]. Both the Ca-S and P-S diet improved mineral retention, while those fed on a Ca-S diet showed a lower prevalence of deformities, close to the size-matched CTi. These results suggest that the requirements of dietary Ca and P were significantly higher in GHTi than in CTi and, consequently, that the conventional levels of Ca and P in commercial diets for CTi cannot meet the mineral requirement of GHTi. We therefore propose to develop an optimal feed to meet the altered nutritional requirements of GH-transgenic Nile tilapia for growth-promoting optimization. This may become prerequisite for rearing this GHTi line in CRASs.