Nutritional value of some small indigenous fish species (SIS) of Bangladesh

Twenty three small indigenous fish species (SIS) in the size range of 3-18 cm were analyzed for proximate composition and minerals (Ca and P) content to evaluate their nutritive value. The moisture content of different species ranged between 71.00 and 81.94%. In general, small sized fishes showed higher moisture content. The muscle protein content among the species varied widely (16.16-22.28%). In general, the muscle protein content of fishes showed higher value than the whole carcass protein content. The carcass lipid content varied between 1.87 and 9.55% and showed an inverse relationship with the moisture content. The gross energy content ranged from 19.51-27.30 KJ/g on dry matter basis. In the present study, the calcium and phosphorus contents ranged between 0.85-3.20% and 1.01-3.29% respectively. The calcium and phosphorus ratio (Ca/P) varied between 0.44 and 2.00. From the nutritional point of view, it shows that the SIS are good source of protein and minerals especially calcium and phosphorus

Evaluation of the carcass and commercial characteristics of carps

The role of carcass evaluation techniques in aquaculture research programs, especially in genetics, breeding, production management, feeding and nutrition, cannot be overemphasized. Knowledge of production efficiencies and growth potentials in relation to desired carcass attributes has provided an impetus to improvements in genetic selection techniques and management of aquatic food animals. Accurate, standard and uniform methods of carcass evaluation are critically important. A standard format developed for collection of data on carps is presented in this paper.

Effects of duckweed (Lemna minor) as dietary fishmeal substitute for silver barb (Barbodes gonionotus Bleeker)

A 60-day long growth trial was conducted to evaluate the suitability of duckweed Lemna minor as dietary fish meal substitute for silver barb (Borbodes gonionotus Bleeker). Five iso-nitrogenous diets were formulated to contain 35% protein and each treatment had three replicates with 15 fish in each aquarium with a mean initial weight of 1.5 ± 0.2 g. Duckweed was used in the experiment to replace 10, 20, 30 and 35% of the dietary fish meal in diet 2, 3, 4 and 5 respectively. Fish meal was used as the sole source of protein in control diet (Diet 1). Fish were fed three times daily at satiation level. In terms of growth, food conversion and protein utilization, the control diet and diet containing 17.07% duckweed showed the best (P<0.05) performance followed by diets containing 34.14%, 51.21% and 59.24% duckweed. Fish fed diets containing higher levels of duckweed had higher carcass moisture and lower lipid content compared to the control diet. Histopathological examination revealed abnormalities in the liver of fish fed diets containing higher inclusion of duckweed. It was noted that 10% of the dietary fish meal protein could be replaced by duckweed (L. minor) in the diet of silver barb (B. gonionotus).

A study on the lipid distribution pattern in muscles of two teleosts, Arius dussumieri and Ophiocephalus striatus

The muscles of the various regions and zones of the body of the two teleosts, A. dussumieri and O. striatus have been analyzed for lipid contents. There is a significant dorsum-ventral gradient in lipid concentration exhibited by both the fishes with higher lipid values in the ventral aspect of the body, especially the belly flaps. As regards the vertical series, both the fishes exhibit comparatively higher lipid contents at the dorsal aspects of the caudal region and at anterior portion of the dorsal fin area with lower lipid values at cephalic and middle portions of the body. The red muscle of Arius exhibits higher lipid content than the white muscle.

Evaluation of some formulated diets for rearing the post-larvae of Macrobrachium rosenbergii

Macrobrachium rosenbergii post-larvae with an average weight of 6.26 ± 0.23 mg and an average length of 10.67 ± 0.13 mm were fed with one of the five experimental diets having graded levels of lipid (5.0, 7.5, 10.0, 12.5 and 15.0%) to satiation two times a day to study their effect on growth, survival and feed utilisation. The highest weight gain was observed in post-larvae fed 7.5% lipid, although there was no significant difference (p>0.05) between groups fed 7.5 and 10.0% lipid. Similar effect was observed in the specific growth rate and protein efficiency ratio of post-larvae fed the diet with 7.5 and 10.0% lipid. The lowest feed conversion ratio was obtained in postlarvae fed the diet with 7.5% lipid. The survival rates of post-larvae fed on various levels of dietary lipid differed significantly (p<0.05) after 15 days of rearing period. Significantly lower survival was observed in the diet with 15.0% lipid level. Dietary lipid did not significantly affect prawn carcass protein, lipid and ash contents. Based on the data analysis (ANOVA – one way analysis), the dietary lipid requirement for 15 days of nursery rearing of Macrobrachium rosenbergii post-larvae was estimated to be 7.5 to 10.0% under experimental conditions in this study.

Analysis of lipid and lipid-fractions of some freshwater fishes and their inter-relationship

Two fish species each from carnivorous (Clarias batrachus, Channa punctatus), omnivorous (Cyprinus carpio, Cirrhinus reba), and plankton feeder (Catla catla, Labeo rohita) were collected from freshwater sources under natural habitat to study their total lipid (TL) and lipid-fractions. Significant relationship between these parameters was also worked out. The variation of total lipid and lipid-fractions in tissues of freshwater fishes were not significantly different (P>0.05). But a higher trend of total lipid and glyceride (TGL) contents were found in carnivores followed by omnivores and least in plankton feeders. The trend was reverse for total phospholipid, cholesterol and free fatty acids. TGL content in all class of fishes was significantly related with TL (P<0.01), phospholipid (PL) (P<0.001), cholesterol (P<0.05), free fatty acids (P<0.05) and monoglycerides (P<0.001). Similarly total lipid was linearly related with total glycerides (TL=-3.02 + 0.10 TGL) and phospholipid (TL=7.13-0.12 PL). From this study it is concluded that almost all lipid-fractions of freshwater fishes can be predicted easily from total lipid content of the tissue.

Effect of phosphorous supplementation in the formulated fish feed on carcass quality of Nile tilapia Oreochromis niloticus L.

A study was conducted to evaluate the effect of phosphorus supplementation in the formulated fish diet on carcass quality of Nile tilapia in net-cages suspended in fertilized earthen ponds. In the experiment 3% di-calcium phosphate (DCP), 3% triple supper phosphate (TSP) and 7% 16:20 inorganic fertilizer were added as phosphorous sources to three diets containing fish meal as main protein ingredient. Feeding tilapia in net-cages with these diets significantly (pcarcass quality and bone phosphorous content of Nile tilapia over fish fed with same diet without phosphorous supplementation and fish given no feed. The final body composition and bone phosphorous content of Nile tilapia fed with DCP, TSP and 16:20 grade fertilizer supplemented diets were comparable.

Recovery, growth and carcass composition following periods of restricted ration and full feeding in indian major carp, Rohu (Labeo rohita H.)

A 90-day experiment was conducted to determine the effect of restricted ration and full feeding on the recovery growth and carcass compositions of fingerlings (average weight - 20.74 ± 0.13 g) of rohu, Labeo rohita (H.). Rohu fingerlings procured from a local fish breeder were fed with commercial pelleted feed (27% crude protein) during the two-week acclimatization in the laboratory condition. Experimental pelleted diet (30% crude protein) was prepared and the control group (T sub(CFR)) was fed at 3% of body weight for the 90-day trial period. The experimental group T sub(1FR) was fed for three days at 1% of body weight and the next three days at 3% of body weight, T sub(2FR) was fed for seven days at 1% of body weight and the next seven days at 3% of body weight, T sub(3FR) was fed for 15 days at l% of body weight and the 15 days at 3% of body weight and T sub(4FR) was fed for 25 days at 1% of body weight and the next 25 days at 3% of body weight, alternating between 1 and 3% for the specified period during the 90-day trial period. Daily rations were divided into two equal meals per day at 09.00 and 16.00 hours. Average percent survival rate of rohu during the 90-day trial period was more than 90. Percent live weight gain (98.90 ± 0.34, 113.0 ± 5.93, 125.71 ± 11.01 and 141.90 ± 2.89), specific growth rate (1.53 ± 0.01 1.68 ± 0.06, 1.80 ± 0.10 and 1.96 ± 0.02%/d) and absolute growth rate (1.33 ± 0.13, 1.38 ± 0.07, 1.39 ± 0.04 and 1.44 ± 0.07g/d) of the experimental groups (T sub(1FR), T sub(2FR), T sub(3FR) and T sub(4FR) respectively) increased with the advancement of the experiment in comparison to those in control, T sub(CFR) (90.92 ± 5.81%, 1.44 ± 0.07%/d and 1.34 ± 0.20g/d, respectively) and were proportionately correlated with the degree of deprivation probably through the mechanism of increased feed intake (hyperphagia), feed efficiency ratio or gross growth efficiency, protein efficiency ratio and the superior feed conversion ratio reflecting in better performance index. The body length and muscle composition of fish indicated that recovery growth happened due to protein growth but certainly not due to fat deposition in the gut. Feeding at 1 and 3% of body weight alternating over a period of 25 days might economize the culture operation of rohu.

Short-term preservation of Brachionus calyciflorus: effects of storage on protein, lipid and carbohydrate contents

The short-term preservation of Brachionus calyciflorus for 45 days at three different temperatures (4, -4 and -20°C) led to decrease in protein, lipid and carbohydrate contents in all the three cases. However, the rate of deterioration was much higher at 4C than at -4 and -20°C. At 4C, protein, lipid and carbohydrate contents reduced by 76.78, 81.11 and 62.83%, respectively, and at -4°C, these were 27.94, 37.46 and 18.42%, respectively, whereas at -20°C, the deterioration was limited to 9.28, 16.44 and 11.35%, respectively, when compared with the control values. Thus, preservation at -20°C is comparatively better as it exerts limited effect on the protein, lipid and carbohydrate contents of B. calycijlorus.

Lipid breakdown in oil sardine (Sardinella longiceps) during frozen storage

The problem of hydrolysis of lipids and consequent accumulation of free fatty acids and development of rancidity due to oxidation of the lipids are major problems in frozen storage of oil sardine (Sardinella longiceps). The course of the phospholipid breakdown, production of free fatty acids and the changes taking place in the major unsaturated fatty acids during frozen storage are described in this paper. The rate of free fatty acid production is faster in the fish, with the higher fat content. Unlike in lean fish, the neutral lipids are found to contribute substantially to the free fatty acid production. The fatty acids most affected during storage are C sub(20:5) and C sub(22:6). The polyene indices were found to decrease during storage. These effects are more pronounced in the fish with the higher fat content.

Some physical properties of the muscle lipid of two freshwater teleosts, Ophicephalus striatus (Bloch.) and Clarias batrachus (Linn.)

Various physical properties (viscosity, fluidity, surface tension and specific gravity) have been determined for muscle lipids of Ophicephalus striatus and Clarias batrachus. Results are presented and the methods used in determination noted. The physical parameters studied are found to be species-specific.

Some changes in the physical qualities of muscle lipid of the freshwater murrel, Ophicephalus striatus (bloch.) during storage

The present communication reports the changes in the specific gravity, coefficient of viscosity, fluidity and surface tension of the muscle lipid of O. striatus, a common freshwater murrel, when stored at room temp (32 ± 2°C) The specific gravity of muscle lipid was found to rise from 0.894 to 0.912 during the first 25 days of storage but registered the highest (0.925) when stored for 50 days. Surface tension seemed to rise with the duration of storage. This was, presumably, due to an increase in the forces with which the molecules in the surface of the lipid tended to compress the molecules below to the smallest possible volume. During the period of storage marked changes seemed to occur in the direction of an increase in the value of the coefficient of viscosity and a reciprocal decline in the fluidity. Evidently, the observed increase in the viscosity seemed to be the result of increased internal friction between different molecular layers of the lipid, whereas a decline in the fluidity was perhaps the consequence of its inverse correlation with the coefficient of viscosity.

Lipid hydrolysis in mackerel (Rastrelliger kanagurta) during frozen storage

The hydrolytic changes in the lipids of mackerel (Rastrelliger kanagurta) during storage at -l8°C were studied with a view to understand the factors involved in the formation of free fatty acids. Only the phosphorylated fraction did undergo hydrolysis at an appreciable rate. It was found that the free fatty acid production was mainly associated with the phospholipid hydrolysis. As regards the triglycerides and unsaponifiable matter, there was no significant change in levels during frozen storage.

Lipid distribution in body and skin of four species of marine fish

The paper presents results of a study on the analytical characteristics of lipids from the skin and muscle of four important species of Gujarat coast fishes. Changes in characteristics like saponification value, iodine value and unsaponifiable matter of these lipids during different months of the year are also reported.