Abstract

Green moray eels (Gymnothorax funebris) under human care are reported to have elevated plasma cholesterol and triglyceride concentrations with development of lipid keratopathy.¹ Nevertheless, serum trace mineral and vitamin analyses have not been assessed, and the complete nutrient content (cholesterol, vitamins, and minerals) of managed eel diets has also not been reported.^1,2 Serum biochemical, trace mineral, and vitamin A and E analyses were performed for three green moray eels managed by Disney's The Seas® and ten recently captured, fasted, free-ranging green morays. Complete nutrient analysis was performed for managed eel diet items and metabolizable energy was calculated.³ Serum cholesterol, calcium, phosphorous, iron, and vitamin E concentrations were greater (p<0.05) in managed versus free-ranging eels. Serum cholesterol and vitamin E positively correlated to body weight (p<0.01). Both eel populations had greater concentrations of serum iodine and lower concentrations of vitamin A when compared with other carnivorous aquatic species. Atlantic herring (Clupea harengus) had the greatest metabolizable energy, crude fat, and iron content but the lowest cholesterol content when compared with capelin (Mallotus villosus) and Ilex squid (Ilex illecebrosus). Squid had the lowest metabolizable energy and crude fat content but greatest cholesterol content. The vitamin supplement (Mazuri Vita-Zu 5TLC) provides 12 g vitamin E/100 g 'as fed' to the managed eel diet. The diet likely contributes to the development of hypercholesterolemia and influences other serum indicators of health in eels under human care. Furthermore, the crude fat content of diet items cannot be used to predict cholesterol concentration.

Acknowledgements

We are grateful for the generous support of the Aquarium and Animal Health teams at Disney's Animals Science and Environment (The Seas®). Aquarists, managers, veterinarians, and veterinary technicians played an essential role in animal management, sample collections, and record keeping. We also greatly appreciate the efforts of the team at Dynasty Marine Associates for obtaining free-ranging eel blood samples and the staff at Marathon Veterinary Hospital for sample processing.

* Presenting author

Literature Cited

1.  Clode AB, Harms C, Fatzinger MH, Young F, Colitz C, Wert D. 2012. Identification and management of ocular lipid deposition in association with hyperlipidaemia in captive moray eels, Gymnothorax funebris Ranzani, Gymnothorax morina (Cuvier) and Muraena retifera Goode and Bean. Journal of Fish Diseases. 35:683–693.

2.  Greenwell MG, Vainisi SJ. 1994. Surgical management of lipid keratopathy in green moray eels (Gymnothorax funebris). American Association of Zoo Veterinarians Proceedings. Pittsburg, PA.

3.  Smith RR. 1980. Chapter 2: Nutritional Bioenergetics in Fish. In: Fish Feed Technology. Food and Agriculture Organization of the United Nations.