Asha Dhawan

Effect of pig dung on water quality and polyculture of carp species during winter and summer

Theeffect of pig dung, as pond manure [at 18 and 36 tha−1 yr−1] and as fish feed ingredient[replacing traditional diet composed of solvent extracted rice bran and mustardcake (1:1) at 25, 50, 75 and 100% levels], was observed on water quality, pondproductivity and survival and growth of carp in polyculture system during winter(12–18 °C) and summer (18–36 °C)months. The studies on water quality parameters viz pH, dissolved oxygen andalkalinity revealed that pig dung even at higher levels (both as manure and /oras feed ingredient) did not deteriorate the quality of water, as all the waterparameters remained within the optimum ranges required for carps. The nutrient(phosphates and nitrates) status of water was significantly better in pondsreceiving pig dung as pond manure at 36 tha−1 yr−1. Pond productivity in terms ofplankton production (phyto and zooplankton) was also significantly higher innutrient rich water (36 tha−1 yr−1) both during winter andsummer. Further, in all the ponds (including control) phytoplankton levels weresignificantly higher during winter and zooplankton was higher during summer. Thestudies revealed 100% survival of all the fish species in all the treatments.During winter, the growth of carp was higher in treatments where pig dung wasused as feed ingredient (at 25% level), whereas during summer growth was higherwhere pig dung was used either as pond manure and/or as feed ingredient (athigher levels). Further, among carps, the growth of Indian major carps vizCatla catla, Labeo rohita and Cirrhinamrigala was higher during summer and that of exotic carps vizCyprinus carpio and Ctenophayrengodonidella was higher during winter.

Impact of organic manures or supplementary diet on plankton production and growth and fecundity of an indian major carp, Cirrhina mrigala (Ham.), in fish ponds

Abstract The paper deals with the qualitative and quantitative analyses of phytoplankton and zooplankton and growth and fecundity of Cirrhina mrigala (Ham.) in ponds receiving cow dung and poultry droppings alone and in combination at 20 000kg ha −1 year −1 , or supplementary diets composed of rice bran and groundnut oil cake (at 2% of the fish body weight). Both phytoplankton and zooplankton and growth rate of fish were significantly higher in ponds receiving poultry droppings alone and in combination with cow dung. However, cow dung alone failed to increase the pond productivity and hence the growth of fish. The contribution of various groups to the plankton population also differed with respect to the manures. Absolute fecundity and fecundity per g ovary weight was greatest in fish reared in ponds treated with poultry droppings alone.

Potential of press mud — a sugar factory byproduct — in supplementary diets and its impact on fish growth

Press mud, a byproduct from sugar factories, was used at different levels in fish diets under a semi-intensive fish culture system and its impact on the growth of common carp, Cyprinus carpio communis Linn was studied. Rice bran in traditional diets may be replaced by up to 50% of press mud to obtain growth of common carp comparable with that on a traditional diet. The common carp makes the optimum use of complex carbohydrates available in press mud.

Effect of zinc on maturation and breeding potential of Cyprinus carpio and Cirrhina mrigala

Effects of safe and sublethal concentrations of zinc were observed on ovarian maturation and breeding potential of carps. Exposure of Cyprinus carpio to 56 and 100 μg/L and Cirrhina mrigala to 560 and 1000 μg/L of zinc for 60 days during each of the preparatory and prespawning phases of reproduction revealed concentration dependent decline in gonado‐somatic index, ova diameter and absolute fecundity complemented with decline in total proteins and total lipids in the ovaries. Exposed fishes were also induced to breed except C. carpio exposed to sublethal concentration.

Toxic effects of industrial effluents on hatchability and viability of Cyprinus carpio eggs

Both field and laboratory studies have revealed that the early developmental stages of fishes are most susceptible to pollutants. Acidification of water and low concentrations of metals and pesticides reduce egg hatchability /viability and larval survival, which are of great concern for recruitment of fishes (von Westernhagen 1988). There have been studies of embryo viability and hatching success of freshwater fishes at low concentrations of single toxicants in clean water (Lockwood 1976; McCormick et ai.1984; Mayes et al. 1986; Dave et al. 1987). However,there is paucity of information on the embryo viability and hatching success of fishes in effluents containing mixtures of organic and inorganic toxicants. Recently, the toxic effects of industrial waste and domestic sewage on embryo viability of rainbow trout, Salmo gairdneri (Fraser and Clark 1984); of pulp and paper mill effluent on egg hatchability of pike, Esox lucius (Tana and Nikunen 1986) and bleached kraft mill effluent on early life stages of brown trout, Salmo trutta (Vuorinen and Vuorinen 1987), have been studied. Hence, the aim of the present study was to examine the effect of different industrial effluents on the hatchability and viability of Cyprinus carpio eggs and to determine their safe levels for discharge.