In the present work an attempt has been made to study energy value of metabolism (respiration or oxygen consumption) in a fresh water teleostean fish, Channa striatus (Bloch) at water temperature 29.5±1.00C. The energy value of total metabolism (R) ranged from 723.1-10390.3 Joule/day/fish within the weight range 9.3 to 103.0 gram fish. The percentage of total energy of food (C) used in the metabolism (R) ranged from 36.0-40.7% with a clear trend of decrease in R value with increasing body weight. The details have been discussed in this paper.

The present study was carried out to evaluate the toxic effect of Chloroxuron (a weedicide) on histopathological changes in the liver of a fresh water teleostean fish, Mystus tengara (Ham.) at sublethal concentrations (0.75 and 0.85 ppm) for 10 and 20 days. After such treatment the liver showed disintegration of hepatic cells, separation of the hepatic cells from the blood vessels and proliferation in the pancreatic tissues with broken blood vessels and atrophy in the nucleus of hepatic cells with broken hepatic cells as compared to control. The details have been discussed in this paper.

In the present work an attempt has been made to study the acute and chronic exposure of a carbamate pesticide, carbofuran on different haematological parameters in an air breathing fish Channa striatus (Bloch). Treatment of sublethal concentration (0.80 mg/I) of carbofuran caused an early increase in RBC count, Hb content and MCHC and decrease in PCV, MCV, MCH and ESR i.e. upto 96 hrs but after 10 days RBC count increased being normal on 30 days. MCV, MCH, MCHC and ESR showed decreasing trend. Recovery studies were also conducted. The details have been discussed in this paper.

This papers deals with oxygen uptake capacity of gills in relation to body weight in a hill stream fish, Garra gotyla (Gray). It was found that oxygen consumption (VO2) increases with the increase in body weight while V02/g/h decreases with the increase in body weight of the fish. The details have been discussed in this paper.

Studies on daily food intake, energy value of ration, total faecal discharge, energy value of faeces and excretory product (U) have been made in different weight groups of an air breathing catfish, Mystus cavasius (Ham.). The above parameters ranged from 0.58-7.14 glfish/day, 2192.4 – 26989.2 joules, 0.071­0.791 g/day/dry wt, 269.66 to 3670.53 joules and 152.07-1889.24 joules respectively within the weight range 12.2 to 102.0g. The details have been discussed in this paper.

The gut content analysis provides the information on food components and feeding habit of fish which is an important aspect for fisheries management. In present study, the qualitative and quantitative analysis of gut content of Indian major carp Cirrhina mrigala from ponds of Sigheshwar, Madhepura; Bihar, were conducted during November 2012 to October 2013. The results on gut content shows that qualitative changes in food component were not found but quantitative changes were observed during the study period. In the gut of fish, food consists of aquatic plant parts (20.12%), phytoplankton (16.46%), zooplankton (19.69%), debris and detritus (22.00%), insects (6.78%) and semi-digested materials (14.83%). The finding suggests that this fish is more suitable for the pond rich in debris and detritus of plant origin.

Leeches are medicinally important, and are non-target organisms as far as the pestcontrol operations are concerned. Leeches become the victims of toxicity of various agrochemicals, pollutants etc. in the freshwater ecosystem, due to which their very existence is unnecessarily threatened. Changes in the protein fractions such as sarcoplasmic , contractile and stromal of skin (botryoidal tissue), anterior sucker and posterior sucker of the leech. Hirudo birmanica were studied after treatment with sublethal concentration of malathion (0.01ppm), for 24, 48 and 96 h. The values of the fractions are presented as mg% on the dry weight basis. Amongst the protein fractions in control leeches the contractile proteins were quantitatively more than sarcoplasmic and stromal proteins in all tissues. The protein fractions decreased progressively and significantly (p<0.05) in all tissues of leeches as the period of exposure to sublethal concentration of malathion increased. The results are discussed in the light of physiological response of leech to pesticidal stress.

The fauna of cestodes are found both in marine and fresh water fishes of different part of our country. The species Puntius is one of the important freshwater fish with high nutritional value and market demand because of its relatively little bit lesser cost and abundance in the fish market. But due to parasitic infection it poses threat to fish cultivation, which is a valuable source of nutritional food and employment. In the present study the survey of IMC and quantification & incidence of the cestode parasite of fresh water fish in Puntius conchonius has become of high concern. These fishes were collected from local fish market Dumraon, Dist. Buxar, Bihar, during the month of January to February 2018. Out of 105 fishes specimens of P conchonius 10 were highly infected with adult cestode parasites. The encountered parasitic species includes Senga spp. & Circumoncobothrium spp.

Biodiversity of aquatic insect and physico-chemical water quality parameters in the Bekarbandh pond was assessed during June 2016 to May 2017. Seven sampling stations, each 100m long were established. Three replicates of samplings by aquatic D frame net were used at sampling sites. A total of 4,257 individual of aquatic insect were collected during one year. 6 orders & 12 families were recorded in this study. The family Hydropsychidae and Chironomidae were the most abundant of aquatic insects that was found in the pond water. The CCA revealed the family Mesoveliidae and Chironomidae were correlated with alkalinity in the pond water, whereas dissolved oxygen was correlated with family Baetidae, Coenagrionidae, Hydrophilidae and Helotrephidae. Signs of increasing water quality deterioration were evident in the result of the physico-chemical analyses.

This study reports histopatholgoical changes in the intestine of the fish Channa punctatus exposed for 30 days to sublethal doses of the water soluble fractions (WSF) of petrol (9.60 ml/L) and diesel (8.70 ml/L) fuels. WSF of petrol induced loss of normal architecture & orientation of villi which became shrunken and atrophied and exhibited interlocking arrangement. Besides, the hyperactive mucous secreting cells together with their nuclei became pyknosed and necrosed indicating signs of apoptosis. More severe nature of degenerative changes were observed under the toxicity of WSF of diesel. These were disintegrating serosa, very ill defined epithelial lining, almost structureless and detached core of mucosal fold as well as ruptured and broken villi leading to heavy exudation of mucus into the lumen. Possible explanations have been discussed and the findings led us to conclude that WSF of both petrol and diesel impair the absorptive capacity of the intestine.