The optimal feeding frequency for largemouth bass (Micropterus salmoides) reared in pond and in-pond-raceway

Abstract

Largemouth bass is a carnivorous fish commercially important for freshwater aquaculture worldwide, however, the optimal feeding regime for the fish reared in pond has not been established. The present study examined feed intake, growth, feed utilization, body composition and waste outputs of largemouth bass fed at different feeding frequencies in pond and in-pond-raceway (IPR). Two 10-week feeding trials (I and II) were conducted simultaneously. Fish were fed at 1, 2, 3 or 4 meal d−1 in pond (trial I), and were fed at 2 or 3 meal d−1 in either pond or IPR (trial II). The initial body weight was 43.0 ± 0.2 g fish−1. In trial I, weight gain increased with increasing feeding frequency from 1 to 3 meal d−1, but no significant difference was found in weight gain between fish fed at 2, 3 and 4 meal d−1. The lowest retention efficiencies of nitrogen (NRE) and phosphorus (PRE) and the highest feed intake and phosphorus waste occurred in fish fed at 4 meal d−1. In trial II, no significant difference was found in weight gain between fish fed at 2 and 3 meal d−1 in IPR, while NRE, PRE and energy retention efficiency (ERE) were lower in fish fed at 3 meal·d−1 than in fish fed at 2 meal d−1. Weight gain, NRE, PRE and ERE were lower, while feed intake, body lipid content, wastes of nitrogen, phosphorus and carbon were higher, in fish reared in IPR than in fish fed at the same feeding frequency in pond. The present study indicates the optimal feeding frequency was 3 meal d−1 for largemouth bass reared in pond, and 2 meal d−1 for the fish reared in IPR. According to production performance, the IPR should not be an appropriate grow-out system for commercial largemouth bass farming.