FORCE FEEDING WITH SYRINGE IN ADULTS OF Hippocampus reidi

High mortality is observed in seahorse aquaculture, which may be related to poor digestibility and assimilation of food, lack of interest in the food and parasites, making animals malnourished and susceptible to diseases. Force feeding with the aid of syringes can be a strategic method for feeding impaired animals that are not able to capture food. This work describes a force feeding method for adult Hippocampus reidi as an alternative to reverse malnourished condition.

Four seahorses H. reidi showed atypical behaviour for the species (tank bottom positioning without substrate attachment, pale body colour, lack of interest and inability to capture food) during 30 days.

Force feeding was tried as a way to change this picture with food being offered with a 1-mL syringe with a tip of 100 µL, cut about 1 cm from the thinnest end (Fig. 1). Food consisted of a mixture of fresh squid, fish, shrimps, and mussels, diluted in seawater to obtain a more pasty/liquid consistency. Vitamin C was added to the mixture in the first 15 days of feeding. The animals were gently restrained by hand to provide feeding twice daily (8:00 and 17:00) (Fig. 1). Temperature (28.1 ± 0.8 °C) and salinity (28.0 ± 1.6) were monitored before the first feeding throughout the treatment.

If animals started to show a more active behaviour and interest in the food offered (frozen shrimp post larvae -PL), force feeding with syringe was gradually replaced by PL.

Gradual recovery of two individuals, by increased swimming activity, interest in food and change in colour (from brown to yellow) was observed. On day 13, the individuals showed interest in PL, higher swimming activity and search for food on the water surface, despite the inability to capture the food. After 19 days, fish were able to capture PL and a gradual increase in faecal content was observed at the bottom of the tank. Mortality occurred in two individuals, which probably reached the point-of-no-return due to the long period of starvation.

The method employed was effective, considering that 50% of individuals returned to their typical diet and behaviour. The force feeding technique proved to be a strategy for recovery of debilitated seahorses, lacking interest in inert food, avoiding the loss of these animals in captivity. Subsequent work might start applying this technique before animals reach the point-of-no-return.

Acknowledgments: National Council for Scientific and Technological Development (CNPq) and Coordination for the Improvement of Higher Education Personnel (CAPES) for their support in research funding.