Aquaculture Feed and Fertilizer Resources Information System

Nile tilapia - Nutritional deficiencies

It is important for farmers to recognise at least the most common nutritive deficiency symptoms. Deficiency signs of farmed tilapia may occur when fish are fed nutrient deficient diets or raised in a low nutrient-input culture system.  Essential amino acid (EAA) deficiency in tilapia generally leads to loss of appetite, retarded growth, and poor feed utilization efficiency (Table 27, EAA/EFA).  In some fish species (e.g. rainbow trout, sockeye salmon, Atlantic salmon, chum salmon, coho salmon), lysine, methionine or tryptophan deficiency results in various signs such as scoliosis, lordosis, fin erosions and cataracts although none of these deficiency signs have been reported for tilapias.   Similar to EAA deficiency, the lack of essential fatty acids (EFA) will also lead to loss of appetite and poor growth in tilapia.  Other reported signs of EFA deficiencies in Nile tilapia include swollen pale and fatty livers.

Mineral deficiencies are difficult assess in tilapia as most trace elements are obtained both from the dietary ingredients and from the culture water (Table 27, minerals). The following deficiency signs have been reported for Nile tilapia: calcium- reduced growth, poor feed conversion and bone mineralization; magnesium- whole-body hypercalcinosis; and manganese- reduced growth and skeletal abnormalities. In a study by Dabrowska et al. (1989) with Nile tilapia, excess magnesium (0.32 percent) in a low-protein (24 percent) diet produced severe growth retardation and showed a significant decrease in blood parameters, haematocrit and haemoglobin content, and magnesium deficiency in a high-protein (44 percent) diet caused whole-body hypercalcinosis. A dietary magnesium content of 0.059-0.077 percent was adequate for optimum performance of this species.

Vitamin deficiency symptoms of tilapia under controlled culture conditions have been extensively reviewed by Jauncey (2000), El-Sayed (2006) and Lim and Webster (2006) and these are summarized in Table 28.  It should be noted that under culture conditions, vitamin deficiency signs are not a common occurrence in tilapia. In fact, several studies have reported on the “non-essentiality” of adding vitamin premixes to tilapia diets (for review, see Jauncey, 2000). Vitamins obtained from natural food in fertilized ponds, endogenous vitamins present in feed ingredients used in tilapia feeds and the microbial biosynthesis of some vitamins in the gut are all likely to contribute significantly to the vitamin requirements of tilapia. Ascorbic acid deficiency is common in intensively cultured fish. This is often due to manufacture error or to improper storage. Indeed, vitamin C is degraded at high temperatures and after long term storage. Moreover it is rapidly consumed when the fish are stressed.

Vitamin E deficiencies cause anorexia, reduced growth and death. It is also a strong antioxidant that protects unsaturated fatty acids. Vitamin E deficiency may also lead to pathological effects as a consequence of oxidized lipids (congestion, hemorrhages, lordosis, exophthalmia etc.) Incorporation of antibiotics into the feed reduces the vitamin synthesizing capacity of fish. For instance, vitamin B12 is entirely produced by Nile tilapia in normal conditions but should be added to the feed when fish receive antibiotic treatments.