Daily rhythm of feeding activity and the ability of Amazon River prawn (Macrobrachium amazonicum) to control its protein intake using self-feeders

Abstract Self-feeding systems have been used to study aquatic animals’ behavior, suggesting initial studies for practical diet design. This study aimed to identify gaps in knowledge of the behavior, feeding rhythms, and target protein intake of the Amazon River prawn ( Macrobrachium amazonicum ) to inform the design of new diets. This study included two trials. In trial 1, under a 12:12 h LD photoperiod, 40 prawns (mean ± SD = 2.18 ± 0.3 g) were divided into four experimental units. A self-feeding system connected by an infrared sensor was prepared. Prawns were allowed to trigger sensors connected to feeders to assess a possible daily feeding rhythm for 52 days. During trial 2, 80 prawns (1.55 ± 0.19 g) were placed inside eight aquariums. The effect of two dietary protein levels (20%P or 40%P) was evaluated on behavioral protein intake target using self-feeding, as well as growth and body composition. The results of trial 1 showed that Amazon River prawn exhibited predominantly nocturnal behavior using self-feeding systems, with higher food intake during this period ( p < 0.05). However, crepuscular behavior was also observed. The trial 2 results revealed a clear protein intake target of 2.4 g per 100 g of body weight (BW). After the diet was switched from 40 to 20P, the prawns’ feed intake increased ( p < 0.05) to compensate for the protein dilution. Diet 40P had significant effects on final weight, weight gain, length gain, specific growth rate and feed efficiency ( p < 0.05). However, diets had no influence on body composition ( p > 0.05). These findings can help to understand feed schedules and nutritional approaches, which are important for new aquaculture species.