We examined heterotrophic bacterial abundance, chlorophyll-a concentration and resources limiting bacterial growth from October 2004 to August 2005 in Lake Phewa. The lake has a large watershed that covers %435 ha of water surface surrounded by %23-time large catchment area that might receive up to 4850 mm annual precipitation. During the study, bacterial abundance ranged from 3.2 to 9.9 · 10 6 cells mL )1 , and chlorophyll-a varied from 2 to 32 lg L )1 . Bacterial abundance and chlorophyll-a weakly correlated (r = 0.40, n = 77, P < 0.1) in the lake. Experiments on resources, glucose (C), nitrogen (N), phosphorus (P) alone and in combination (CNP) limiting bacterial growth rate, were examined using dilution bioassays. Experimental bottles enriched with resources and controls without enrichment (in triplicate) were incubated in situ for 48 h at collection depth. Results showed that C, N and P in combination significantly (at 5% level) stimulated bacterial growth rate. Bioassays with single resource additions showed P as main nutrient limiting bacterial growth comparing with C and N, implying that rainfall received in the catchment might convey adequate resources causing increased P deficiency for bacterial growth in Himalayan foot hill Lake Phewa.

Efficient fish marketing needed for the growth of fish production as well as development of fishery sector. Domestic fish markets development in the Nepal will plays a very crucial role in the development of fisheries sector. Fish marketing system development in Nepal is in infant stage. Fish marketing channel has not been systematic in Nepal. The fish marketing infrastructure and the facilities for the fish market should be developed by identifying the possible production and collection centers in the country. Live fish have getting higher price in the market and fish imported from India price is lesser than fresh wet fish of Nepal. Government policy needed to upgrade the existing fish marketing system to ensure supply of hygiene fresh fish and processed fish for consumers. Int. J. Appl. Sci. Biotechnol. Vol 7(1): 1-5

Anaesthetic agents are very useful for reducing the stress caused by handling, sorting, transportation, artificial reproduction, tagging, administration of vaccines and surgical procedures in fish. The efficacy of two anaesthetics: MS-222 and AQUI-S â were tested on rohu, Labeo rohita advanced size fry. The lowest effective doses that produced induction in 3 min or less and recovery times 5 min or less and meet the most criteria of good anaesthetic characteristics were 125 mg L À1 of MS-222, and 30 mg L À1 of AQUI-S â in rohu, Labeo rohita advanced size fry. Induction times were significantly decreased with increased in the concentrations of any of the two tested anaesthetic agents. The lowest doses suitable for transportation of rohu advanced size fry observed were: 10-15 mg L À1 of MS-222 and 2.5 mg L À1 AQUI-S â . Both anaesthetics showed promising to be used as anaesthetics for handling and transportation in rohu (Labeo rohita) advanced fry.

Fry rearing is one of the important stage which aims at obtaining high growth and survival for production of fingerlings required for stocking into grow out ponds as well as rehabilitation in natural habitat. This experiment was conducted with the purpose to test the effect of dietary crude protein level (CP %) of feeds prepared from similar feed ingredients in different ratios on growth performance and survival rate of Rohu fry (Labeorohita). An initial density of 100 fry/m 2 was maintained in hapa fixed in the cemented tank. The dietary CP% level of feed tested were 20% CP, 25% CP, 30% CP, and 35% CP fed at 5% body weight. The experiment ran for 53 nursing days. The results showed that there was no significant difference (P > 0.05) in the growth rate (g/day) of fry among treatments. Rather group fed with higher protein level grew comparatively better indicating possibility of increasing need of protein in diets. However, the survival rate (%) of rohu fry was significantly different (P < 0.05) in each tested CP% level of feed. Highest survival (82%) of fry was found in the feed of CP 35% and lowest (56%) in the feed of CP 25%. It was predicted that feed with increasing level of CP % in diet is essential for increasing survival rate.

In order to understand trophic status of lake Phewa, largest lake (535 ha) in Pokhara valley, seasonal pattern of zooplanktons, chlorophyll a and nutrients level in water column was examined from January to December 2005. Total zooplanktons density was highest in January and November, showed bimodal pattern in Lake Phewa. The sequence of dominant species of zooplankton was Nauplius > Kerratella > Cyclops > Daphnia > Eodiaptomus in this lake. Correlation between zooplankton species and nutrients level was established. The Chlorophyll- a as an indicator of phytoplankton biomass peaks in November and chlorophyll-a concentration was found lower in winter months. The NH4-N ranged between zero to 0.021 mg/l with mean of 0.003 mg/l. The annual concentration of nitrate+nitrite (NO3+NO2) was found upto 0.148 mg/l (mean= 0.013 mg/l), soluble reactive phosphate (PO4-P) ranged from zero to 0.003 mg/l (mean= 0.001 mg/l), and total phosphorous ranged upto 0.052 mg/l (mean= 0.009 mg/l) in lake Phewa in 2005. Based on nutrients and chlorophyll-a dynamics, the lake varied from mesotrophic to eutrophic in different seasons. The Phewa Lake fluctuated from oligo-mesotrophic in monsoon seasons to meso-eutrophic in dry periods. Key words: Zooplanktons, nutrients, chlorophyll. DOI: 10.3126/eco.v16i0.3473ECOPRINT 16: 51-57, 2009

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Knowledge on nutrient dynamics of the lake provide basis for modality and extent of exploitation of fishery resources. Therefore, a long-term data of physico-chemical parameters was analyzed for the assessment of changing aquatic environment and its impact on aquatic biodiversity. The physical and chemical properties of water have been changed over 14 years (1994 to 2007). Increase in mean annual concentrations of dissolved oxygen in recent years (2002 to 2007) were recorded in the lake, which indicate improvement in water quality due to lake restoration. Annual mean pH levels were not consistent to produce specific trends. The pH of the water increased from 1994 to 2002, and then decreased continuously in later period. Water transparency increased with the decreased chlorophyll 'a' concentration during 1999 to 2002 due to degraded condition. The higher concentrations (0.010- 0.017 mgl-1) of soluble reactive phosphorous (SRP- PO4) were recorded during 1994 to 2000, later SRP concentration (0.003-0.012 mgl-1) tend to reduce. Effect of fluctuation in the physico-chemical properties on the lake productivity in terms of fish yield was assessed.

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