On the effect of electrical field on Indian carps in captivity

Threshold current densities required for narcosis of fish in captivity differed in different species. Increased temperature of the water had greater effect on the fishes while changes of pH had no appreciable effect on narcosis in the fishes. Impulse currents of 50 V were found to have better effect on the fishes than continuous current of 180-220 V.

Toxicity of four therapeutic compounds to fry of Indian major carps

Toxicity of four therapeutic compounds: sodium chloride, potassium permanganate, potassium dichromate and acriflavine to fry of Catla calla, Labeo rohita and Cirrhinus mrigala was tested. Bioassays were conducted in 5 and 10 liters glass jars in the laboratory for periods of 24-48 hrs. at temperatures of 26° and 32°C. LC 50 values of the chemicals were in the ranges of 5500 to 7500 ppm, 37.5 to 48 ppm, 92.5 to 125 ppm and 47.5 to 80 ppm respectively. The results obtained are of value in evolving cheap control methods against some common fish diseases. Sodium chloride and acriflavine can be widely used for chemotherapy and potassium dichromate is preferable to potassium permanganate for prophylaxis.

A study on length-weight relationship, food and feeding habits of Indian scad, Decapterus russelli (Ruppel, 1830) along the northwest coast of India

Length and weight relationship of Decapterus russelli (Ruppell, 1830) is worked out to be W = 0.00312 L³ which indicates the isometric growth of the fish. Study on food and feeding habits revealed that the species is carnivorous, pelagic, feeding primarily on small crustaceans and small fish species, viz. Acetes indicus, ostracods, Apogon sp., Leiognathus sp., sciaenids, Netnipterus japonicas, Myctophid sp., Trichiurus sp., Therapon sp., D.russelli and occasionally on prawns. It is a selective feeder on Aeetes indicus.

Effects of periphyton grown on bamboo substrates on growth and production of Indian major carp, rohu (Label rohita Ham.)

The effects of periphyton, grown on bamboo substrates, on growth and production of Indian major carp, rohu, Labeo rohita (Hamilton), were studied in 10 ponds during July to October '95 at the Bangladesh Agricultural University, Mymensingh. Five ponds were provided with bamboo substrates (treatment I) and the rests without bamboo substrates (treatment II). It was revealed that there had been no discernible difference in the water quality parameters between treatments. A large number of plankton (30 genera) showed periphytic nature and colonized on the bamboo substrates. The growth and production of fish was significantly (p<0.05) higher in the ponds with bamboo substrates as compared to the ponds without substrates. The net production of rohu in treatment I was about 1.7 times higher than that of treatment II. Fish production was as much as 1899 kg/ha over a culture period of 4 months in the periphyton-based production system.

Energetics of resting metabolism in an Indian major carp (Catla catla Ham.)

Resting metabolism in Indian major carp, Catla catla Ham. fingerlings were investigated. For this purpose a water recirculatory system in the laboratory was used. The metabolic energy losses were determined by the indirect method of oxygen consumption by the fish and were then multiplied by an oxycalorific coefficient (Q-ox). Five metabolism chambers in the experimental system were used where there were two same treatment runs in quadruplicate of mean total weight of fish fingerlings of 109.5, 110.4, 112.8 and 111.6g/chamber. The water temperature in the system was 28±0.5°C. The mean metabolic rate in the replicates showed no significant variation (p>0.05) and was found to be 151.66, 153.91, 150.25, 152.74 mgO-2/kg/h respectively. This showed an equivalent energy loss 5.40, 5.52, 5.51 and 5.56 KJ/chamber/day (35.60, 35.92, 36.67 and 36.40 KJ/kg/day) respectively. Energetics of resting metabolism in an Indian major carp (Catla catla Ham.)

Pathogenicity of Aeromonas hydrophila artificially infected to Indian major carp (Cirrhinus mrigala Ham.)

Abrasion, feeding, injection and immersion methods were used to evaluate the pathogenicity of five different strains of Aeromonas hydrophila viz. RG (rui gill), ML (mrigal lesion), SG (sharpunti gill), F1K (mrigal kidney), GFL (gold fish lesion) and Ah-19 (Aeromonas hydrophila-19, Ref. Strain) against C. mrigala H. Bacterial suspension containing viable cells of 7.5x 10⁵ per ml was found to be very effective in intramuscular injection and feeding resulting 100% mortality after 96hr of inoculation. The strain RG, ML and F1K produced scale loss with erosion of the skin surface with/without hemorrhagic lesion after 48hr of inoculation following abrasion method. The strains SG and Ah-19 resulting scale loss with erosion of the skin surface with/without hemorrhagic lesion after 72hr of inoculation following abrasion and injection methods. SG and F1K caused reddening in mouth region after 72hr of feeding inoculation, whereas RG resulted frank ulcers from eroded dermal layer exposing underlying musculature which was hemorrhagic after 96hr of inoculation by abrasion method.

Histological distribution and ultrastructure of exocrine pancreas in Indian major carp (Labeo rohita Ham.) and its alteration in aflatoxicosis

The distribution pattern of exocrine pancreas in Labeo rohita besides its general location along the course of intestinal mesentery was studied. It is evenly distributed within the liver around portal vessels and also within the spleen near a blood vessel. On ultrastructure, two cell types of different degrees of staining intensities containing abundant rough endoplasmic reticulum, mitochondria, pre-zymogen and zymogen granules were marked. During aflatoxicosis, the mesenteric pancreas and hepatic pancreas were mostly affected revealing necrotic changes to acini. The zymogen granular activities were markedly reduced. Ultra structurally, the rough endoplasmic reticulum was fully dilated and formed whorled pattern. The damage to the exocrine pancreas might be affecting digestive enzymes' secretion which may be one of the causes of aflatoxin-induced anorexia in fish.

Feeding metabolism in an Indian major carp (Catla catla Lin.) fed on different protein diets

Feeding metabolism in an Indian major carp, Catla catla fingerlings of 10.8+0.56g was investigated in a flow-through water recirculating system. The metabolic energy loss in resting metabolism and feeding metabolism were determined by the indirect method of oxygen consumption followed by multiplication by suitable oxycalorific coefficient. This was done in four metabolic chambers of a respirometer system. Ten fish fingerlings of mean total weight of 109.5, 110.4 and 112.8g/chambers respectively each in two experimental runs of three treatments a, b and c were used. The mean resting metabolic rate during unfed condition showed no significant variation in different treatments. The fish in three treatments a, b and c fed on diets containing 28, 33 and 38% crude protein had significantly different (p<0.05) post-fed SDA magnitude of 497.7, 638.7 and 735.5 mgO2/chamber/day having an equivalent energy loss of 12.68, 14.68 and 15.86 KJ respectively. The SDA co-efficient in three treatments a, b and c were 14.95, 19.00 and 22.36% respectively whereas, respiratory energy - 'R' as % of mean total ingested energy in three treatments were 26.93, 31.17 and 34.74% respectively showing a significant increase (p<0.05) with increase of protein. Feeding metabolism in an Indian major carp (Catla catla Lin.) fed on different protein diets.

Effects of animal and plant protein diets on growth of Indian major carp (Labeo rohita Ham.) fingerlings

An experiment was conducted with Labeo rohita fingerlings in an indoor static fish rearing water system of glass made aquaria. Five experimental diets A, B, C, D and E were formulated containing 33% dietary protein level in five treatments each having two replicates containing 12 fingerlings of mean total initial weight of 13.00±0.2g. Sixty days of feeding trial in this experiment showed that fish fed on diet 'A' containing fish meal and diet 'E' containing mixed plant sources protein had significantly highest and lowest growth respectively. However, no significant difference of growth was found in fish fed on diets C and D containing meat and bone meal, and mix of animal protein source diets respectively. The result showed that the apparent protein digestibility (APD) of diets 'A' and 'E' had significantly best and least values respectively. Food conversion ratio (FCR) and protein efficiency ratio (PER) ranged between 1.37 to 2.17 and 1.38 to 2.18 respectively. On the basis of observed FCR and PER diets 'A' and 'E' produced significantly highest and lowest growth respectively.

Pathology of mixed infections of saprolegniasis-myxosporidiosis in Indian major carp (Catla catla Ham.)

An outbreak of saprolegniasis in Catla catla in composite carp culture ponds were recorded during winter season. The typical cotton wool growths were observed on whole body surfaces of catla along with sporadic mortality. The fungal invasion was only restricted to skin and no fungal elements were visible in any internal organs after periodic acid schiff staining. On histology, periportal accumulation of mononuclear cells in liver, presence of myxosporidean cysts in antieror kidney, eosinophilic granular cells reaction in submucosa of stomach and intestine, dilated and engorged blood vessels of brain along with sloughing of epidermis and hyperplasia at gill lamellar base were pronounced changes. The possible role of release of Saprolegnia toxin in producing internal organs pathology has been discussed.

Acute toxicity of chlorpyrifos, cadusafos and diazinon to three Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) fingerlings

Fingerlings of three Indian major carps, viz. Catla catla (Hamilton-Buchanon), Labeo rohita (Hamilton-Buchanon) and Cirrhinus mrigala (Hamilton-Buchanon), were exposed to different concentrations of chlorpyrifos (lorsban 10 G), cadusafos (rugby 10 G) and diazinon (basudin 10 G) for a period of 96h with a view to determine the median lethal concentrations (LC sub50) values for each of chemicals. Of the tested concentrations, chlorpyrifos at a dose of 6.65 ppm, cadusafos at 2.0 ppm and diazinon at a dose of 8.40 ppm or above induced 100% mortalities within 96h of exposure. The 96h LC sub50 values of chlorpyrefos, cadusafos and diazinon were 1.66, 0.72 and 2.10 ppm for C. catla, 2.35, 0.72 and 2.97 for L. rohita and 2.35, 0.72 and 2.10 ppm for C. mrigala, respectively. Pesticide induced behavioral abnormalities observed in the present study included erratic movements, rapid operculum activities, jumping of fish out of the test media, violent spasm and convulsion.

Fishery potential along the Indian coastal waters between Porbandar and Ratnagiri

As part of the ongoing marine pollution monitoring programme the coastal stretch between Porbandar and Ratnagiri was considered to assess the fishery potential. Regular experimental trawling was done off Porbandar, Veraval, Diu, Hazira, Daman, Bassein, Bombay, Murud and Ratnagiri at a depth range of 5-25 m during 1988 to 1992. The catch rate varied from 1.2 to 225 kg/h (av.20.3 kg/h). Zonewise maximum catch (av.56.8 kg/h) was observed off Ratnagiri followed by off Porbandar (av.30.1 kg/h), off Bombay (av.23.9 kg/h) and off Murud (av.19.8 kg/h). The area between Hazira and Daman was poor in fish catch. In general, the catch rate showed a fluctuating trend during the period of observation. Among the hundred species identified from the collections the most common species were Coilia dussumieri, Johnius glaucus, Scoliodon laticaudus, Lepturacanthus savala, Harpadon nehereus, Sardinella longiceps, Pampus sp. and Congresox sp. The community structure and species assemblage at different zones are discussed in detail.

Role of vitamin E in growth of an Indian major carp, Catla (Catla catla)

A feeding trial was conducted to study the role of vitamin E in growth of Catla catla fry. Newly hatched larvae of Catla were fed with synthetic diet, supplemented with graded levels of vitamin E α0, 50, 100, 150, 200, 250 mg/Kg of diet. The spawn were fed with five times of their body weight for 30 days. Observation was made on the basis of survival, growth, daily weight gain and food conversion ratio. The significant weight gain and highest survival could be achieved by the diet supplemented with 150 mg of vitamin E per kg of the diet. The weight gain per day in 0, 50, 100, 150, 200 and 250 mg vitamin F/kg supplemented diet were 4.0, 5.2, 6.5, 7.8, 6.8 and 6.3 mg, while survival was 50, 51.8, 52.4, 52.8, 52.2 and 52% respectively.

Use of dopamine antagonists on induced spawning of Indian major carps

To test the efficacy of the technique of using dopamine-antagonists with pituitary extracts, experiments were conducted in July/August '93, at the CIFE Fresh water Fish Farm, Powerkheda. In all, 35 sets (1 female x 2 male in each set) were tried individually. 19 sets were treated with Domperidone (DOM) and Carp Pituitary Extract (CPE) and they constituted the experimental sets, while the rest 16 were treated with CPE and formed the control sets. The breeding, complete ovulation and hatching was 84.2%, 87.5% and 85.7%, respectively in the experimental sets whereas it was 93.7%, 60% and 72.7%, respectively in case of control sets. Experimental sets yielded 1.20 lakh spawn/kg body wt. (female) as compared to 0.83 lakh spawn kg body wt. (female) received from control sets on average basis. When DOM was used at 50-60% there was 100% breeding success but when increased to 70%, breeding rate fell to 66%. In mass breeding of Catla in the circular hatchery DOM mixed with CPE in 50:50 ratio gave excellent results.

Observation on the urinogenital papilla and sexual dimorphism in some Indian gobiids (Gobiidae: Teleostei)

A thorough comparative study on the urinogenital papilla and sexual dimorphism has been made for the first time in both the sexes of twelve Indian gobiids: Glassogobius giuris (Hamilton); Acentrogobius cyanomos (Bleeker); Eleotriodes muralis (Valenciennes); Parapocryptes serperaster (Richardson); Apocryptes bato (Hamilton); Scartclaos viridis (Hamilton); Boleophthalmus boddarti (Pallas), Periophthalmus schlosseri (Pallas); P. koelreuteri (Pallas); Taenioides anguillaris (Linnaeus); T. buchanani (Day); Odontamblyopus rubicundus (Hamilton). The urinogenital papilla, originating as a free muscular organ from the ventral surface of the body-wall and shortly behind anus, is present in both the sexes. It is an important organ of primary sex recognition in all species. In case of male the papilla is conical, broad at the base and in female it is either flattened, distally truncated or bluntly rounded. The presence of permanent colour mark over the specific region of the body surface is another secondary sexual character in a few species. Besides, colouration may also be a nuptial secondary sex character developed in some during peak breeding season. The enlargement and colouration of the organ is subject to seasonal variations parallel to the seasonal gonadal cycle. The histological architecture of the papilla shows a high degree of cellular specialization and an interrelationship to the urinary and genital ducts. The functional efficacy and significance of the papilla in the breeding biology of these fishes has been discussed.