Oyster mushroom waste as manure in fish culture: a preliminary study

In an attempt to recycle the waste substrates of the oyster-mushroom crop, tanks were stocked with seed of Indian major carp Cirrhinus mrigala at the rate of 600,000/ha and waste substrate was applied at weekly interval at 0, 50, 100, 150, 200 and 250 g/tank. Oyster mushroom waste not only provided highly nutritive colonised detritus to the fish as direct feed, but also produced rich plankton in the tank. In waste treated tanks, production was better than in the control in 150, 200 and 250 g/tank treatment suggesting the possibility of fish-oyster mushroom integration.

Evaluation of stern trawler operation in the Wadge Bank for economic exploitation of its demersal fish resources

The records of the exploitation of demersal fish resources by trawlers during the past two decades indicated a decline in productivity and uneconomical fishing operations. The possible reasons for the decline can be deduced by analysis of the fishing records of trawlers that have fished in the banks. Such an analysis can also provide a basis for planned management in the exploitation of demersal stocks of fish. This paper attempts to provide such a basis for the Wadge Bank.

Production and economic return in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix) in farmers' ponds

The production of fish and net economic return in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix) in farmers' ponds were assessed. The experiment was arranged in three treatments each with three replications. The ponds were stocked with 30,000 fishes per hectare. In treatment 1 (T1) pangasiid catfish only, in treatment 2 (T2) pangasiid catfish and silver carp at the ratio of 1:1, and in treatment 3 (T3) pangasiid catfish and silver carp at the ratio of 2:1 were stocked. At harvest, production of fish was found significantly (p<0.05) different among the treatments, highest in T1 and lowest in T2. Though the total biomass production and total economic return was significantly highest in T1 than in T2 and T3, the net economic return was lowest because of the required highest input costs especially for supplemental feed and fingerlings, resulted the highest cost per unit yield (CPY in Tk/kg) in T1. Highest cost for supplemental feed required in T1 was due to highest quantity of feed required for the highest number of pangasiid catfish stocked in that treatment. The findings of the present study suggest that though monoculture of pangasiid catfish give higher fish biomass production but polyculture with silver carp is environmentally good and economically profitable.

Distribution of vitamin B-12 in some fishes and marine invertebrates

Distribution of vitamin B-12 in the skeletal muscle of several marine and fresh water fish and marine invertebrates are reported. The vitamin B-12 content of white muscle of various fish ranges between 0.05 and 1.5 micrograms. The elasmobranch fish, such as sharks and rays, has a lower levels of vitamin B-12. The distribution of vitamin B-12 in the red muscle, heart, brain and liver of various fish is also shown. Content in red muscle varies between 3 and 22 micrograms, averaging 8 micrograms. The values show that the heart is a rich source of vitamin B-12. Internal organs are also rich in vitamin B

Salinity and survival of Martesia striata (Linn) in Cochin harbour

The effects of salinity variations on the survival of Martesia striata from Cochin harbour are presented. It is observed that at least a few of the animals survive the low saline conditions during monsoon. Laboratory experiments showed the lethal salinity as 6‰ when animals acclimatised in 34‰ were subjected to abrupt changes in salinity. But acclimatisation to 17‰ salinity showed a downward shift in the lethal salinity to 4‰. The present observations indicate that M. striata is euryhaline arid the extent of tolerance to lower salinities depends on the degree of acclimatisation.

Studies on preservation of fish in refrigerated sea-water

Storage characteristics of oil sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta) and seer (Scomberomorus guttatus) in refrigerated sea-water (RSW) were studied in comparison with their storage in crushed ice. Oil sardine stored in RSW was found to be comparable to iced ones only during the initial stages (up to 2 days) of storage and on further storage the former was found to be inferior to the latter. RSW can be advantageously employed for preservation of mackerel and seer. Mackerel and seer could be stored in RSW in acceptable condition for 4 to 6 days and 12 to 14 days respectively.

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.

Solid loss and weight gain in prawns during storage in ice

Loss of solids from and gain in weight of meat of whole prawn and prawn meat stored in ice has been studied to explain the mechanism of solid loss. Two stages are identified in this phenomenon. In the first stage water is absorbed without loss of solids resulting in a maximum increase in weight. In the second stage both solids and water are lost resulting in gradual decrease in weight from the maximum reached but not reaching the original weight. It is inferred that whole prawns stored in ice up to two days give the maximum peeled yield without loss of nutrients and at the same time making the peeling process easier.

Maze model to study spatial learning and memory in freely moving monkeys

Many types of mazes have been used in cognitive brain research and data obtained from those experiments, especially those from rodents' studies, support the idea that the hippocampus is related to spatial learning and memory. But the results from non-huma