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ARS Home » Southeast Area » Stuttgart, Arkansas » Harry K. Dupree Stuttgart National Aquaculture Research Cntr » Research » Publications at this Location » Publication #125335
Title: MASSIVE HEPATIC NEROSIS AND NODULAR REGENERATION IN LARGEMOUTH BASS FED DIETS HIGH IN AVAILABLE CARBOHYDRATES.

Author
item GOODWIN, ANDREW - UAPB
item LOCHMANN, REBECCA - UAPB
item TIEMAN, DARLENE - UAPB
item Mitchell, Andrew

Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2001
Publication Date: 12/15/2002
Citation: GOODWIN, A.E., LOCHMANN, R.J., TIEMAN, D.M., MITCHELL, A.J. MASSIVE HEPATIC NEROSIS AND NODULAR REGENERATION IN LARGEMOUTH BASS FED DIETS HIGH IN AVAILABLE CARBOHYDRATES.. JOURNAL OF THE WORLD AQUACULTURE SOCIETY. 2002. v.33. p.466-477.

Interpretive Summary: Largemouth bass are raised in ponds and sold in Asian fish markets on the east and west coasts of the United States. Largemouth bass that normally eat live fish or crustaceans can be trained to eat prepared diets with diligent effort. In the winter of 1998, a major producer of bass trained to eat prepared diets suffered a significant increase in shipping-related and in-pond mortality. Massive liver lesions were also observed. The losses and the lesions were found to be associated with the feeding of commercially prepared fish diets with 45% protein, 25% fat and 27% or greater carbohydrate. By feeding a diet formulated with 45% protein, 25% fat and 21% carbohydrate no significant losses were reported, liver lesion were significantly reduced and significantly better growth was observed.

Technical Abstract: In the winter of 1998, a major producer of bass trained to eat prepared diets suffered a significant increase in shipping-related and in-pond mortality. Livers of affected fish were pale and translucent with large 3-10 mm yellow to pink nodules on their surface and in the parenchyma. Histological examination of these livers showed that they contained few hepatocytes, were primarily composed of connective tissue and inflammatory cell types. The nodules appeared to be areas of multifocal regeneration of normal hepatocytes. Sequential studies of bass in ponds revealed that the bass were progressively accumulating glycogen in their hepatocytes. A 12-week feeding trial was conducted in aquaria with juvenile largemouth bass to determine the effect of diets varying in available carbohydrate on fish growth, survival and liver glycogen content. A trout diet, a Steelhead trout diet, and a test diet all with 45% protein and 25% fat diet contained 35, 27, and 21% carbohydrate, respectively. Weight gain was lowest in fish fed the extruded trout diet, while liver glycogen was significantly higher in fish fed diets with >27% carbohydrate. After switching to the test diet on the farm it was noted that sixteen-month-old fish examined in October 2000 had no hepatic nodules or necrosis, were significantly larger than those of previous crops, and the farmer experienced no significant losses in ponds or during shipping.