Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Effects of Addition of Tilapia on the Abundance of Periphyton in Freshwater Prawn Culture Ponds with Periphyton Substrates

Mr. Md. Nahid Hasan
MS Fellow
Bangladesh Fisheries Research Institute, Shrimp Research Station, Bagerhat, Bangladesh

Abstract/ Executive Summary:

An experiment was conducted to evaluate the effect of addition of tilapia on abundance of periphyton in freshwater prawn, Macrobrachium rosenbergii (de Man) in periphyton based culture system for a period of 120 days at Fisheries Field Laboratory Complex, Bangladesh Agricultural University, Mymensingh. A large pond (83×8.9 m) was drained completely and partitioned by galvanized iron sheet into 18 small ponds of 40 m² each; of which 6 ponds were used for this experiment. The experimental ponds were divided into 2 treatments each with 3 randomly selected ponds. The absence and presence (0 and 0.5 individual m^-2) of tilapia (Oreochromis niloticus) were investigated in 40 m² ponds stocked with 3 prawn juveniles (5±0.05 g) m^-2 with added substrates for periphyton development. A locally formulated and prepared feed containing 30% protein was supplied considering the body weight of prawn only. Addition of periphyton substrates significantly reduced the inorganic N-compounds (TAN, NO₂-N, and NO₃-N) in water column. Forty six genera of periphyton were identified belonging to the Bacillariophyceae (10), Chlorophyceae (21), Cyanophyceae (7), Euglenophyceae (2), Crustacea (1) and Rotifera (5) with significant difference (P<0.05) of phyto-periphyton except Euglenophyceae and without significant difference (P>0.05) of zoo-periphyton between the treatments. The abundance of periphyton biomass in terms of dry matter, ash, ash free dry matter and chlorophyll-a were significantly higher in tilapia-free ponds comparing to tilapia added ponds. Benthic organisms had no significant difference (p>0.05) between the treatments. Addition of tilapia in periphyton-based system benefited the freshwater prawn culture through (i) reducing toxic inorganic nitrogenous compounds in water (ii) reducing demand for supplemental feed (iii) using periphyton as additional natural feed and, (iv) improving survival and production of prawn and tilapia.

Keywords: Periphyton, Freshwater prawn culture, Tilapia

Location: Fisheries Field Complex of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh,

Start Date: 20-02-2008

End Date: 20-06-2008

Program Area: Animal Health and Management

Commodity: Prawn, Tilapia

Objectives:

To evaluate the effect of addition of tilapia on abundance of periphyton in freshwater prawn, Macrobrachium rosenbergii (de Man) in periphyton based culture system

Methodology:

The experiment was conducted at the Fisheries Field Complex of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, for a period of 120 days from 20 February to 20 June 2008 in six ponds having an area of 40 m²each. The ponds were rectangular in shape, well exposed to sun light, independent, and having water supply facilities. The water depth was maintained to a maximum of 01 m over the study period. The surrounding of all ponds was covered by 01 m height nylon net to prevent the entry of predators like birds, snakes, frogs and others. The experiment was conducted under completely randomized design (CRD). Two treatments were tested each of which was replicated. All undesirable fish were completely eradicated by applying rotenone at a rate of 2.5 g/m³. Aquatic weeds were removed manually. The grasses of the pond dikes were also cut into small size by using scythe. After one week of rotenone application, lime (CaO) was applied at a rate of 250 kg ha^-1. Three days after liming, ponds were fertilized with urea and triple super phosphate (TSP) each at a rate of 25 kg ha^-1 and cow dung at a rate of 1,000 kg ha^-1.The shelter was built by bamboo branch (locally known as kanchi) with date tree leaves and was installed in each pond before stocking with prawn juveniles to provide shelter for prawn. About 436 bamboo with a mean diameter of 0.05 m were posted vertically into the bottom mud of each pond, excluding a one meter wide perimeter water surface from the dike. This resulted in an additional area for periphyton development equaling about 60% (i.e. 24 m²) of the pond surface area. Ponds were not fertilized during the grow-out period. After the first fertilization and before prawn stocking, the ponds were left 10 days to allow plankton development in water column and periphyton growth on bamboo kanchi. Juveniles of Macrobrachium rosenbergii (5± 0.05g) procured from a nearby commercial hatchery were stocked at 3 juveniles m^-2in the ponds and juveniles of Oreochromis niloticus (24.3± 0.24g) from the Bangladesh Fisheries Research Institute (BFRI) were stocked according to the experimental design. Juveniles of freshwater prawn were fed with processed palleted feed containing 30.03% crude protein daily at a rate of 10% of the body weight for the 1^st month, 7% for 2^nd month and 3% for the rest of the culture period. Half of the required feed for a day was supplied in the morning and rest half in the evening. Feed requirement was calculated and adjusted after monthly sampling of prawn. Locally purchased tapioca starch was used as carbohydrate source for manipulating the C/N ratio. In order to raise the C/N ratio to 20 in all the ponds, 0.9kg tapioca starch was applied for each kg of formulated feed. The pre-weighed tapioca starch was mixed in a beaker with pond water and uniformly distributed over the pond surface directly after the feed application at 7.00 am. Phyto and zoo-periphyton enumeration: Plankton samples were collected monthly from each pond. A bucket contained two litres of water was used to collect 10 litres of water from five different places and depth of the pond and passed through a fine mesh (25 μm) plankton net. The concentrated samples were transferred to a measuring cylinder and carefully made up to a standard volume of 50 ml with distilled water. Then the collected plankton samples were preserved in 10% buffered formalin in small plastic bottles each for subsequent studies. From each of the 50 ml preserved sample, 1 ml sub-sample was examined using an S-R cell (Sedge Wick-Rafter cell S50, Microlitre) under a binocular microscope (Olympus, M-4000D, Japan) with phase contrast facilities. One ml sub-sample from each sample was transferred to the cell and then all planktonic organisms present in 10 squares of the cell were identified and counted. Identification of plankton to the genus level was carried out using the Keys from Ward and Whipple (1959), Prescott (1962) and Belinger (1992). For each pond, mean number of plankton was recorded and expressed numerically per litre of water. Plankton density was calculated using the formula of Azim et al., 2001b. N= (P X C X 100)/L Adult freshwater prawn were harvested and counted for total number separately from each plot to evaluate the survival rate. After direct counting, weight and length of each individual prawn was also taken.For the statistical analysis of the data, a one-way ANOVA and DMRT were done by using the SPSS (Statistical Package for Social Science) version-11.5. Significance was assigned at the 0.05% level. Duncan’s test was used to test the results of multiple ranges for comparisons of averages.

Source of Information: J. Bangladesh Agril. Univ. 10(2): 313–324, 2012, ISSN 1810-3030

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The addition of periphyton substrates increased survival rate of prawn. Final weight and weight gain were significantly higher (P<0.05) in treatment PT₀ than those in treatment PT_0.5. Specific growth rate was significantly higher in PT₀ than in PT_0.5. The addition of tilapia decreased the gross and net yield of prawn. Tilapia had significant effects on FCR of freshwater prawn, substrates decreased FCR by 13.5% whereas addition of tilapia increased 16% gross yield.

Knowledge Management: Journal