Edit: removed as Mr. Thompson replied.
I thought you might be referring to this paper:
Suboptimal nutrition may contribute to lionfish (Pterois volitans and Pterois miles) health issues in managed care environments. This study’s objective was to establish and compare whole blood fatty acid profiles in wild and aquarium lionfish. Whole blood samples were dried onto specialized...
www.mdpi.com
Can you summarize the thesis for me? I have the grandson tonight, and I'm just not able to synthesize that much data (grin). I did notice that she referenced my 2015 fish disease book multiple times. I've updated that material since then, here is the current text from the 2023 edition:
Fatty liver disease (Hepatic lipidosis)
A major chronic health problem facing most long-term captive fishes is “fatty liver disease,” or liver degeneration. Fish do not assimilate fats well, so often, if a fish's diet is too high in fat, it will then be deposited in various tissues, especially the liver. Unlike with mammals, this fat is not readily usable during times of starvation. Even if food is withheld from a fat-laden fish, very little of the fat is ever reconverted into usable energy. Some fish do not show outward signs of obesity, especially sedentary species such as groupers and lionfish. In these, fatty liver disease may only be diagnosed after death, when sections of the liver will show oil droplets and pieces of the liver itself will float in sea water. With many animals, a period of acute anorexia can cause liver damage.
Fatty liver disease is most common in adult fish whose growth rate has slowed considerably. Younger fish tend to grow fast enough to minimize fat deposition—excess calories are turned into muscle tissue instead. With long-term captive fish, fatty liver disease is the leading cause of (or contributor to) death. Virtually every lionfish held in captivity longer than three years will show evidence of fatty liver disease upon necropsy.
What techniques are available to solve this problem? Nothing can be done for a fish once fatty liver disease has become evident. Prevention is the only course of action an aquarist can take. Simply putting the fish on a "diet" may not work, in that this may result in increased aggression towards other fish in the aquarium. The best solution is to avoid feeding herbivores diets high in meat proteins and to train carnivores to feed on low-protein, low-fat diets such as squid or gelatin diet. Also, avoid feeding any saturated fats to fish. Overall dietary fat levels should be less than 16% in actively growing fish and less than 9% in adult fish.
Vitamin E supplementation is often used in an attempt to prevent fatty liver disease and liver degeneration, which is one of the top chronic health problems of captive fishes. Even with vitamin E supplementation you can still see fatty liver disease issues, either due to vitamin E depletion as a result of feeding slightly rancid (peroxide containing) feeds, or because other aspects of the fatty acid metabolism incorrect, such as feeding cold water fish species to tropical fishes.
There has also been a theory that feeding freshwater fish to predatory marine fish will cause malnutrition and fatty liver disease. Most of the rationale behind this has to do with slightly different fat profiles between marine and freshwater prey fish species. Credence is given to the theory when so many marine aquarists report that they lost their lionfish to liver degeneration after feeding them live freshwater goldfish (See the next section for an alternative hypothesis regarding issues with feeder goldfish). In reality, they would have run into the same trouble had they fed any single fish species as a diet for their lionfish. Feeding carnivores too frequently can also cause fatty liver disease. The general recommendation is to feed larger carnivores only twice a week.
Jay
