2.1 Sampling sites The extensive field survey was made to identify the feed ingredients mostly used in aqua farms in Narsingdi Region (23º55'28.52"N and 90º45'12.06"E). Rice bran, maize, wheat meal, mastered oil cake, meat and bone meal, earth worm, crab hard cover, dried fish and mollusk fish meal were identified as used feed. Rice bran, maize, wheat meal and mastered oil cake are available in our country, but animal origin is imported from foreign. These collected feed ingredients are used in grower stages of fishes such as Rui, Silver Crap, Pangus, Koi, Shingi and Tilapia etc.
2.2 Data collection Primary data were collected mostly from farmers while secondary data were collected from research papers, book, Fisheries Resource Institute, thesis paper and term paper.
2.3 Sample collection and preparation Samples were collected from different area of Narsingdi and immediately after collection samples were taken to the Nutrition Laboratory of Institute of Marine Science & Fisheries, University of Chittagong for proximate composition analysis of moisture, ash, protein, lipid & carbohydrate.
2.4 Method of proximate analysis These analyses show the moisture, crude protein, crude lipids, ash and carbohydrate content of the sample. 2.5 Determination of Moisture Moisture contents in the feed were determined by. The percentage of the moisture content in the sample was calculated by the following formulae: % of moisture = {weight of original sample – weight of dried sample) / weight of original sample} ×100.
2.5 Determination of Ash Ash content of each feed was estimated by following incineration method [14]. Calculation: % of ash= (weight of ash ÷ weight of sample) × 100 2.6 Determination of Crude Protein: Micro kjeldhal method as used to determine the crude protein.
2.7 Determination of Crude lipid Fat is examined with low boiling organic solvent (petroleum ether/ diethyl ether, xylem) by soxhlet extraction and the extract thus obtained weighed after recovery of the solvent. Crude fat was determined through Soxhlet extraction technique sing hexane (65 ºc-70 ºc) as the solvent.
Calculation % of crude fat = (corrected weight of fat ÷ weight of sample) × 100 % of carbohydrate = 100 – (moisture + ash + protein + fat)