Studies on the preparation of fish silage. 1. Effect of quality of raw material and type of acid

An experiment was undertaken in which silver bellies (Leiognathus splendens) of different quality were used to produce silages using different concentrations of hydrochloric acid and formic acid. The quality and storage life of the various preparations are reported. Silages which keep for at least 30 days can be produced from silver belly held for 3 or 12 hours at 28°C by: 1) reducing the pH by addition of hydrochloric acid; 2) adding 0.5% formic acid and reducing the pH to 3.5 with hydrochloric acid; or 3) adding 2.5% formic acid.

Studies on the preparation of fish silage. 2. Rate of liquefaction in different parts of silver belly

An experiment was undertaken to determine from which part of silver belly (Leiognathus splendens) carcasses originate the autolytic enzymes responsible for liquefaction of silage. Findings show that it is important to leave head and viscera present in order to get a satisfactory liquefaction in silage prepared from silver belly using 3.5% formic acid. The storage life of silage produced from various parts of the fish carcasses is also discussed.

Studies on the preparation of fish silage. 3. Dried silage products

An investigation was undertaken on the production of dried products from silver belly (Leiognathus splendens) silage mixed with plant filter materials. Silages produced using hydrochloric acid and/or formic acid when mixed with rice bran or maize meal and dried, yielded powders having an acceptable appearance and a pleasant odour, which are suitable for use in compounded chicken feeds.

Studies on the preparation of fish silage. 4. Economics of production

Economic aspects of producing liquid and dried silage from silver belly (Leiognathus splendens) in Sri Lanka are considered. A discounted cash flow analysis for the production of a dried fish silage/rice bran product suitable for use in compounded poultry feeds shows that the internal rate of return for a 10-year project would be between 34-77% and for a 5-year project between 26-73%. Thus it is concluded that the project would be extremely profitable.

Studies on fecundity of Puntius sarana (Ham.) in relation to total length, total weight and ovary weight

A total of 43 mature female of Puntius sarana (Ham.) ranging from 204 mm to 320 mm in length and 102 to 482 g in weight were used for present studies. The relationship between fecundity with respect to total length (TL), total weight (TW) and ovary weight (OW) was found to be linear. The coefficient of co-relation 'r' of the above relationships was found to be 0.5947, 0.5761 and 0.9837 respectively. All these values are highly significant (P=0.01) indicating a close relationship between these parameters. However, as indicated by value of 'r' (0.9837), the fecundity is more closely related to ovary weight and hence the ovary weight may be a better index of fecundity than the total length or weight.

Studies on fecundity of Rita pavimentata (Gunther) in relation to total length, total weight and ovary weight

A total of thirty eight ripe ovaries from the specimens of Rita pavimentata, measuring 230 to 355 mm in total length (TL) and 250 to 750 g in total weight (TW), were selected to study the fecundity. The relationship between fecundity 'and total length (TL), total weight (TW) and ovary weight (OW) was found to be linear. The coefficient of co-relation 'r' of the above relationship was found to be 0.92, 0.94 and 0.96 respectively. All these values are highly significant (P=0.01) indicating a close relationship between compared parameters. However, as indicated by value of 'r' (0.96), the fecundity is more closely related to ovary weight and hence the ovary weight may be a better index of fecundity than the total body length or weight.

Studies on the food habits of three species of Mastacembelidae

To identify the food habits of three species of Mastacembelidae namely Mastacembelus armatus, Mastacembelus pancalus and Macrognathus aculeatus, the gut content analysis was performed by three methods i.e. occurrence method, points method and index of fullness method. All three species were found to consume prawn, molluscs, insects, earth warm, debris and plant materials. M. armatus and M. pan cal us were found to feed mainly on animal food items and 84.68% of different types of animal food were taken by M. armatus and 62.72% by M. pancalus. M. aculeatus was found to consume 44.86% of different types of animal food items, 53.51% of debris and plant materials which indicated that this fish feeds almost equally on animal and plant food. Analysis of the food habits showed that both M. armatus and M. pancalus are carnivore in nature with higher feeding preference for animal food namely prawn, crabs, fishes, molluscs etc. On the other hand, M. aculeatus is an omnivore in nature feeding almost equally on animal and plant food.

Phycochemical studies on sterols from three brown seaweeds of northern Arabian Sea

Three brown algae i.e. Dictyota hauckiana Nizamuddin, Levringia boergesenii Kylin and Spatoglossum variabile Figari et De Notaris, collected from the coastal areas of Karachi, have been investigated for their sterol composition. Four sterols with cholesta skeleton including a new one, 17α-hydroxy-24β-vinyl cholesterol have been isolated from them. Their structures were elucidated with the help of spectroscopic analysis. The new sterol has been named as hauckiosterol after its first source of isolation.

Studies on geo-morphology, ecology and fish production of the 92 rivers of Rajshahi Division, Bangladesh

Geo-morphology, ecology and fish production of the 92 rivers of Rajshahi division have been presented in this paper. Fifteen rivers are dead and 11 rivers have severe erosion problem. Siltation has increased in 66 rivers and depth has decreased in 11 rivers. Sixty nine rivers are suffering from low flow conditions. Fish diversity has decreased in 20 rivers while fish production has declined in 75 rivers. A total of 31 fish species have extinct, 25 species are under threat of extinction and 43 species have low production. Siltation and pollution are the major causes of fish habitat loss. Recommendations are made to protect and conserve fish habitat and riverine fisheries of Rajshahi division.

Studies on the age and growth of Labeo calbasu (Hamilton) with an exploitation pattern from the Ganga River system, Uttar Pradesh (India)

Samples were collected to study the age and growth of Labeo calbasu (Hamilton) from the river Ghaghra (Guptarghat centre, Faizabad). The scales of L. calbasu have been used for age and growth studies in present paper. Study of the marginal rings on the scales of L. calbasu indicates their annual nature. The fish attained growth in 1st 18.7 cm, 2nd 27.8 cm, 3rd 35.7 cm, 4th 41.8 cm, 5th 46.9 cm, 6th 54.9 cm and 7th 57.4 cm years of the life. The growth rate was observed 18.7, 9.1, 7.9, 6.7, 5.1, 8.0 and 2.5 cm for 1st to 7th age classes respectively. The age groups 1+ to 4+ constituted 91.17% of the total exploited population and 8.83% of remaining age groups (5+ to 7+). The maximum exploited population was observed in 2+ age group with 33.68%. Overall exploitation pattern was systematic and a good indicator for heavy recruitment.

Studies on water quality and fish diversity of Sadatpur lake in Ahmednagar district Maharashtra

The present study deals with the water quality and ichthyofauna of Sadatpur lake. Monthly changes in water quality parameters such as temperature, pH, dissolved oxygen (DO), total alkalinity, chlorides, sulphates, phosphates and nitrites have been studied for a period of one year beginning from January 2005 and were investigated to assess the suitability of this lake for fish and fisheries practices. All the physico-chemical parameters determined, revealed that the fluctuations in water temperature, pH, dissolved oxygen, alkalinity and nitrites, were within the desirable limits. On the other hand, chloride and sulphate were lower whereas phosphate was higher than the desirable limits. Altogether 24 fish species belonging to 17 genera and 2 orders were found to be present in the lake. Among fish species family Cyprinidae dominated the lake. The lake subsistence fishery served the need of local fishermen community.

Studies on frozen storage characteristics of fillets from six species of fresh water fishes

Frozen storage characteristics of fillets from six major species of fresh water fishes namely, Labeo rohita, Catla catla, Cirrhina mrigala, Labeo calbasu, Mystus seenghala, and Wallago attu are reported. The biochemical, bacteriological and organoleptic changes in the frozen fillets during storage at -18°C have been followed systematically. Compared to the two species of fresh water cat fishes, the four species of carps studied, had a slightly better storage life. From the organoleptic point of view, fillets of Cirrhina mrigala had the best shelf life.

Studies on equilibrium moisture content of canned prawn with particular reference to drained weight

Drained weight of canned prawn depends on moisture content of blanched meat and equilibrium moisture (EM) content of processed meat. The greater the difference between the two values the more is the fluctuation in drained weight. EM is a fixed value with particular reference to the species of prawn, which has been justified mathematically and by material balance of can contents before and after processing.

Utilization of trash fish for human consumption. 3: Studies on the development of fish pickle from Nemipterus japonicus

A method for the preparation of fish pickles from a lean variety of fish namely pink perch (Nemipterus japonicus) is described. Dipping the fish in 10% sodium chloride solution containing 6% acetic acid before pickling, was found desirable for retaining the meaty texture of the product. The product has no fish smell or flavour and has a shelf life of more than six months at ambient temperatures and scored very well in organoleptic tests.

Studies on the suitability of producing value-added products from silver carp, Hypophthalmichthys molitrix

Silver carp, Hypophthalmichthys molitrix is contributing significantly to the total production of fish through aquaculture in Bangladesh. However, its low market price has become a serious concern to the fish farmers. The suitability of silver carp mince for the production of various value-added products (VAPs) - surimi, fish sausage, fish burger and fish stick was studied during April-September 2000 to ensure more appropriate and profitable utilization of silver carp. Surimi/frozen mince block was produced by washing the silver carp mince with 0.1% NaCl for 7-8 min (4-5 min agitation and 3-4 min settling). A two-step heating schedule for incubation at 50°C for 2 h and cooking at 95°C for 30 min gave high textured good quality consumer product. With the addition of cryoprotectants, surimi could be kept frozen for 5 months without loosing [sic] much of its textural and sensory qualities. Mince-mix and a batter with different ingredients and spices were formulated to produce fish burger using potato smash as the binding agent. Fish flake-mix and a batter with different ingredients and spices were formulated to prepare fish stick using both potato starch and potato smash as filler ingredients. Unwashed and washed frozen mince block or fresh flesh of silver carp was used to prepare fish sausage by heating at 100°C for 1 h after incubating at 50°C for 2 h. A spice-mix formulated with various local spices at the rate of 1.0-1.2% gave good texture and flavor to the sausage. A good-appeared sausage-pink color was developed by combining three food-grade colors of asthaxanthin. Products prepared with potato starch, potato smash and rice smash had an acceptable bacterial load in refrigeration (5°C) for up to 8 days and in room temperature (28°C) for up to 3 days. No coliform bacteria were found in the products prepared.