Md. Asadujjaman
Department of fisheries and Live Stock, University of Rajshahi, Rajshahi-6205, Bangladesh.
Md. Abul Kalam Azad
Department of fisheries and Live Stock, Ministry of Fisheries and Livestock, Bangladesh.
Md. Rayhan Ali
Fisheries and Marine Resource Technology Discipline, Khulna University, Khulna-9208, Bangladesh.
Md. Akhtar Hossain
Department of Fisheries, University of Rajshahi, Rajshahi-6205, Bangladesh.
Azolla, Weed based aquaculture, Polyculture, Production, Economics, Macrophytophagous
At the Alampur village of Sadar Upazila under the Kushtia district, Bangladesh.
Animal Health and Management
Carp fish, Algae, Pond
The study was conducted for a period of six months from April 2012 to September 2012 at the Alampur village of Sadar Upazila under the Kushtia district, Bangladesh.
A total of 9 ponds (average water area of 0.18ha and depth of 1.9 m) was selected for the present study. All the ponds were rain-fed and well exposed to sunlight. The experiment was designed under Randomized Completely Block Design (RCBD) with three treatments (T1, T2 and T3) of carp stocking densities each with three replications. The treatment assignment was as T1: 40 fish/decimal (10000 fish ha-1), T2: 45 fish/decimal (11500 fish ha-1) and T3:50 fish/decimal (12500 fish ha-1). A stocking ratio / combination of fish species was same for all the treatments. Aquatic weeds were removed from all the ponds manually. Predatory fish and other unwanted species were removed through repeated netting. All the ponds were facilitated well with Azolla bank. Liming was done at a rate of 250 kg ha-1before 7 days of fertilization. All the ponds were fertilized with cow dung (1500 kg ha-1), urea (60 kg ha-1) and TSP (60 kg ha-1) as basal dose. One tenth area of the research ponds was used as Azolla bank. Azolla bank was prepared by bamboo fencing (locally called ‘Bana’). In Azolla bank, compost manure was deposited (2470 kg ha-1). Azolla seeds were introduced in Azolla bank at the rate of 1000 kg ha1 for available supply of Azolla at the culture period. Fishes were stocked in all ponds after five days of basal fertilization. All the ponds were stocked with seven species of fishes (mean initial weight of Hypophthalmichthys molitrix, Catla catla, Labeo rohita, Cirrhinus cirrhosus, Cyprinus carpio, Ctenopharyngodon idella and Barbonymus gonionotus were 60, 65, 58, 52, 61, 70 and 22 g respectively). Fish seeds were collected from local government fish farm. Stocking of fish seeds were done at early morning. Stocking density and stocking ratio/combination. After stocking, TSP was applied (2.5 kg ha-1day-1) for ponds under all treatments as periodic fertilization. In ponds under all treatments, Azolla (100%) was supplied as supplementary feed daily at the rate of 100% of the body weight of herbivorous fishes (C. idella and B. gonionotus). Azolla was supplied from Azolla bank and made available 24 hours per day.
Some important water quality parameters of the experimental ponds such as water temperature, transparency, dissolved Oxygen, pH, alkalinity and CO2 were monitored fortnightly during the present study. Water temperature was recorded with the help of a Celsius thermometer at 20-30 cm depth of water. Transparency was measured by a secchi disc. Dissolved oxygen (DO), pH, alkalinity and free carbon dioxide (CO2) was determined by the help of a HACH kit (FF-2, USA). At least 10% (by number) of the fish in each pond were randomly sampled on a monthly basis with a cast net. On each sampling day, individual fish from each pond were weighed and measured. The purpose was to determine fish growth in weight and to adjust the ration. Following growth parameters were used for the present study. Weight gain (g) = Mean final weight (g) - Mean initial weight (g) Final weight (g) = Weight of fish at harvest (g) Specific Growth Rate (SGR, % bwd-1) = [Ln (final weight) – Ln (initial weight)] / culture period (days) x 100.
2.2 Statistical analysis Data on water quality parameters, fish production and economics under different treatments were subjected to one way ANOVA (Analysis of Variance) using computer software SPSS (Statistical Package for Social Science, version-11). The mean values were also compared to check the significant difference from the Duncan Multiple Range Test.
International Journal of Fisheries and Aquatic Studies 2016; 4(4): 273-279
Journal