Dietary selenium requirements of juvenile grouper, Epinephelus malabaricus

Meta-analysis of literature data on mineral and trace element requirements of fish was performed with the major objectives of identifying appropriate response criteria and the factors affecting the minimal dietary inclusion levels. The primary data set included 25 studies on available P, 20 on Ca, 24 on Mg, 5 on K, 37 for Zn, 23 for Se, 19 for Mn, 16 for Fe and 13 for Cu. Broken line regression analysis with linear plateau model (P, Ca, Mg and K) or two-linear line model (Zn, Cu, Fe, Mn and Se) was used for determining the minimal dietary inclusion levels. Vertebral mineral concentration (P, Ca, Zn and Mn), whole-body mineral levels (Mg, K and Fe) and hepatic enzyme activity (Se) were found to be the most appropriate criteria for the respective minerals analysed. In general, weight gain as the criterion resulted in a lower estimate (by 18–42%) than those obtained using whole-body or vertebral mineral concentrations as response criteria. The analysis also showed that different fish species do not show large variations in the mineral and trace element concentrations in the whole body and tissues. Factors such as species group and digestive physiology, type of experimental diet used and dietary interactions, type of mineral source and mineral concentration of water were found to affect the minimal dietary inclusion levels of certain minerals. Besides the meta-analysis, research needs in mineral nutrition of fish with reference to growing changes in dietary strategies and rearing systems are discussed.

Mineral requirements of fish: a systematic review

Information concerning mineral nutrition of fish and marine crustaceans is rather limited compared to that available for terrestrial animals; however, significant advances have been made in recent years. This article summarizes pertinent information about mineral nutrition of fish and marine crustaceans, including classification and general functions of the minerals; dietary essentiality and/or quantitative requirements; bioavailability and dietary interactions; and general recommendations for dietary supplementation. Dietary requirements for approximately ten minerals (calcium, copper, iodine, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc) have been identified for fish, and seven minerals (calcium, copper, phosphorus, potassium, magnesium, selenium, and zinc) have been recommended for inclusion in penaeid shrimp and lobster feeds. Based on current literature, it is clear that when evaluating the dietary essentiality of a mineral, not only growth must be evaluated, but als...

Gamal El Naggar

Papers

Potassium requirement of fingerling channel catfish, Ictalurus puntatus