A feeding experiment was conducted for 135 days to observe the effect of different isonitrogenous (35% crude protein) and isocaloric (385 kcal) diets on the growth and carcass composition of giant freshwater prawn, Macrobrachium rosenbergii (De Man 1879). Three experimental diets (ED1, ED2 and ED3) were prepared using locally available ingredients. These diets differed mainly in terms of percent contribution of major protein sources such as fish meal, soybean meal, groundnut oil cake and mustard oil cake. Experimental diets were evaluated against a commercial diet, which served as the control (CD). Juveniles 1.87–2.44 g in size were stocked at a population density of 40 000 ha−1 and fed thrice daily at 10% in the beginning and reducing gradually to 7% and 5% of the body weight during the experimental period. No significant differences (P>0.05) in the growth performance were observed; however, a significantly (P<0.05) higher yield (721.9 kg ha−1 135 days−1) was recorded for prawn fed with control diet, followed by experimental diet 2 (676.5 kg ha−1 135 days−1, having soybean meal as a major protein source). The survival ranged between 63.8% and 77.7%, with different diets showing significantly higher survival. The apparent feed conversion ratio values of diets ranged between 3.15 and 3.49, with experimental and control diets showing non‐significantly lower AFCR values. At the end of the experiment, representative specimens from each treatment were collected and their carcass composition was measured. Analysis of variance showed that carcass protein and total carbohydrate contents were significantly (P<0.05) higher in prawns fed on a fish–soybean meal‐based diet (ED3) and a control diet. The total lipid contents of prawns, however, did not differ significantly among the various dietary treatments. The results of our study suggest that the experimental diets could be used effectively for M. rosenbergii without compromising growth and flesh quality.

The rate at which triploid grass carp, Ctenopharyngodon idella, consumed two plant species from different locations was measured and compared to the chemical composition of the plants. Grass carp fed on Elodea canadensis from three lakes at significantly different rates (P<0401), but did not eat Elodea densa from two of the sites at different rates. Feeding rate of the grass carp was positively correlated to the concentration of calcium (r=0.976) and lignin (r =0.946), but negatively correlated to the content of iron ( r = -0.808), silica (r= -0.934) and cellulose (r = -0.922). Multiple regression analysis revealed that calcium and cellulose content were the most important predictors of consumption rate. These experiments demonstrate that water chemistry may affect palatability and could in part be responsible for some of the discrepancies in grass carp consumption rate and preference studies.

Six different types of fish patties were prepared from de-boned meat of three weight groups (250 500 g, 501-750 g, and 751-1,000 g) of an Indian major carp, Labeo rohita, using two extenders (boiled potato and corn flour). The weight of the fish and the type of the extender affected the nutritional quality of the patties. Cooking lowered the crude protein but increased the total lipid, total soluble sugars, and contents of the patties. Cooking yield increased with an increase in the weight of the fish. Similarly, the use of corn flour as the extender resulted in a higher cooking yield and higher fat retention capacity than boiled potato. The type of extender had no effect on the water-holding capacity of the patties. The weight of the fish and the extender had no significant effect on appearance, colour, flavour, taste, and the overall acceptability of the product. However, the patties prepared from 250-500 g and 501-750 g weight groups with corn flour as the extender had a significantly higher score for their texture. The total plate count suggested that the patties were safe (from microbiological point of view) up to a storage period of 80 days.

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Fish patty from common carp (Cyprinus carpio Linn.) which has low consumer preference due to the presence of intramuscular spines was developed and the effects of fish weight and the type of extender on product quality were determined. Six different types of fish patties were prepared by using the fish belonging to 3 weight groups (250-500 g, 501-750 g, and 751-1,000 g) and using 2 extenders (boiled potato and corn flour). Patties containing potato had higher moisture (70.6-73.3%), protein (31.5-32.7%) and lipid (3.3-4.6%) contents than those with corn flour (60-65.2, 27.8-33.3, 2.6-3.8%, respectively). Cooking decreased protein but increased lipid, soluble sugars, and gross energy contents of patties. Corn flour used patties gave higher cooking yield than those with boiled potato. These also had higher fat retention capacity and gross energy values. The 501-750 g group patties containing boiled potato had significantly higher scores for texture and overall acceptability.