Abstract
Field experiment was conducted to evaluate the growth performance of monosex tilapia using homemade feed with Peninsula Group fish meal and commercially available feed with local fish meal in earthen mini ponds from June-September 2010. Three ponds (T1) were supplied with prepared feed and the other three ponds (T2) with commercially available fish feed. Fish were fed at the rate of 10% of their body weight for the first thirty days then gradually reduced to 6% for the next ten days, 2% for the next ten days and 3% for remaining days. The temperature were ranged from 31.5-33.0°C, DO from 5.5-15 mg L-1 in T1 and 6.5-14 mg L-1 in T2, pH from 7.1-8.0 in T1 and 7.1-7.7 in T2, alkalinity from 105-160 mg L-1 in T1 and 100-145 mg L-1 in T2, nitrate was 0.06 mg L-1 in both treatments and ammonia from 0.02 and 0.04 mg L-1 in T1 and T2, respectively. The results of the present study showed that the best weight gain was observed as 123.48 g in T1 than T2 (111.82 g). The Specific Growth Rate (SGR) was recorded 3.09 and 2.97 and the Food Conversion Ratio (FCR) was 1.51 and 1.40 in T1 and T2, respectively. There was significant (p<0.05) variation among the survival rate (%) of fishes which were 75.55 and 90.37% in T1 and T2, respectively. The fish productions were 19076 and 16312.11 kg ha-1 in T1 and T2. The highest net profit (Taka/ha/70 days) of Tk. 15, 83,213 was obtained with T1. So, the prepared feed showed better performance with monosex tilapia in compared with commercial fish feed with local fish meal.
NTRODUCTION
Monosex tilapia (Oreochromis niloticus) is a fast growing popular cultivable fish (Chowdhury et al., 1991; Shamsuddin et al., 2012). It can easily survive in derelict water bodies at minimum oxygen level and wide range of temperature and eat all types of feed (Hussain et al., 1989). They may be cultured with low inputs which are locally available. Monosex tilapia is high yielding, excellent breeder and efficient converter to organic and agricultural wastes in to high quality protein, very hardy and resistant to disease, tolerant to over crowding conditions and able to grow in either fresh or brackish water. Tilapia, an omnivore, is assumed to be reared on number of cheaply available foodstuffs containing sizeable amount of carbohydrate. Monosex tilapia growers generally use different supplemental feeds in culture. Only natural food cannot afford high production in commercial monoculture system. Traditionally, fish meal is the preferred dietary protein source for many farmed fish species and is appreciated for its amino acid balance, vitamin content, palatability and un-identified growth factors (Azim et al., 2012; Soltan et al., 2008). Fish meal is considered the most desirable animal protein ingredient in aquaculture diets (Al Mahmud et al., 2012) because of its high protein content, balanced amino acid profiles, high digestibility and palatability and as a source of essential omega-3 polyenoic fatty acids. Among the Southeast Asian countries, Bangladesh in particular abounds with hundreds and thousands of seasonal water bodies in the form of ditches, shallow ponds, road side canals and borrow pits which retain water for 4-6 months, where carp species can not be cultured. No doubt, these water bodies have tremendous potential for aquaculture of fish species with short life cycle and characteristics of faster growth rate and require low input support (Hussain et al., 2000a). Though tilapia is not yet a widely cultured species in South Asian countries, however, its culture practices is increasing rapidly in Bangladesh. There are many homestead derelict mini ponds; proper use of those ponds with any short time culture fish like tilapia can open a new avenue for the poor farmers of Bangladesh.
Thus the aim of the present investigation was to observe the growth performance of monosex tilapia in mini earthen mini ponds using homemade feed and commercial feed.
ATERIALS AND METHODS
The experiment was conducted in 6 experimental ponds each of 0.60 decimal, located in the northern side of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh. The study was carried out for 70 days from 26 June to 03 September 2010. The water depth was maintained at a level of 1.0-1.3 m.
To eradicate all undesirable fish, insect and other aquatic organism ponds were drained out completely. Aquatic weeds were removed manually. Lime was applied at a rate of 1 kg/decimal. Lime was soaked for overnight in a metallic container and then applied by spreading homogeneously in the ponds.
Two treatments were considered having 3 replicates in each, treatment 1 conducted with prepared feed (having Peninsula Group supplied fish meal) and treatment 2 conducted with commercially available fish feed named Quality Fish Feed (nursery-2, starter). The fries of monosex tilapia were supplied by Agro-3 Fish Hatchery and Culture farm, Bailor, Mymensingh and transported to the pond site with polythene bags having oxygenation facilities. The proximate compositions of feed ingredients were determined by using standard methods. A prepared feed (55.24% protein) composed of 37.24% fish meal, 15.00% mustard oil cake, 18.38% rice bran, 18.38% maize, 10% wheat flower and 1% vitamin premix was used in T1. Fish were fed at a rate of 10% of their body weight for the first thirty days then was gradually reduced to 6% for the next ten days, 2% for the next ten days (because, during the period water temperature was suddenly increased between 35-38°C) and 3% till the termination of the experiment. The water quality parameters were recorded throughout the experimental period. Water samples were collected between 9:00-10:00 a.m. at fortnightly interval. The physico-chemical parameters like temperature (°C), dissolved oxygen (mg L-1), pH, alkalinity (mg L-1), nitrate (mg L-1) and ammonia (mg L-1) were determined at fortnightly i
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