Coaxing finicky marine fish to eat prepared foods can be frustrating. Eric Michael Sanchez gets busy in the kitchen...
For some species, and at certain juvenile stages, a lack of food for more than 48 hours can prove fatal. Thankfully we’ve now made significant recent strides in marine care knowledge to coerce many stubborn fish on hunger strikes to dine on our offerings in the marine aquarium.
However, certain species, because of their dietary requirements, should simply not be kept. It’s our responsibility to research a fish’s individual needs before purchasing it in the first place - and there are numerous species that are just not suitable for keeping in an aquarium. They would die there.
Typically there are two reasons why a marine fish may refuse to eat. It could be because the fish does not recognise the prepared meals you are offering as food - or it may be suffering from anorexia or lack of appetite. Both issues can occur simultaneously or independently.
Lack of appetite is typically a side effect of stress or illness and this can often be overcome with good husbandry.
We must first eliminate any potential stressors, including boisterous tank mates. For this reason I would strongly urge quarantining any sickly individuals and all new arrivals from your other fish.
Not only is a disease-free display tank paramount, it allows new fish to adapt to aquarium life more easily and encourages them to gain body mass. This will give the specimen a significant advantage once placed into an aquarium with already established fishes.
Training picky feeders
Training finicky fish to recognise prepared meals as food is a significant problem. Speed up this process with grazing fish by disguising their food. This works particularly well with problematic angelfish and butterflyfish which are not used to eating out of the water column.
Make a food spread to smear and coat live rock rubble, shells, or even coral skeletons. This places the food in and on a surface where the fish would naturally search.
The idea is to first get food and energy into the fish and then help it move on to other prepared foods. As the fish picks at the paste some will enter the water column and slowly it will associate the floating substance as food.
This spread should include seafood/shellfish and some marine specific pellet food. Optional food additives could involve Selcon and garlic.
A variety of frozen or fresh seafoods can be used and in this example a seafood mix of clams, shrimp, and nori (a dried seaweed available cheaply from Chinese supermarkets) is used along with frozen Mysis shrimp.
Again Selcon or garlic are optional additives to increase nutritional value and/or enhance the smell of the paste to further tempt the fish.
Finely chop the ingredients. Be aware of the size of the fish’s mouth to determine what size of particle to create.
Use a spoon or blunt tool to crush the pellets to a spread consistency.
With a small piece of rock, coral skeleton or shell and smear the food paste on to the skeleton. In this case we used an old snail shell, as the fussy eater in question, a Blueline angelfish (Chaetodontoplus septentrionalis), showed interest in snails and Hermit crabs.
Place in the freezer. Because we are not using a binding agent like gelatin, we must freeze the paste-laden shell. From here it is ready to feed. By relying on the freezer to bind our spread it creates a ‘time- released’ food.
We hope the fish will initially take to the spread on the shell or rock and then start to eat from the water column. Once it does, the frozen food and pellets can be fed in a normal fashion. Remove all uneaten food after one to two hours to prevent the water fouling.
Foods for picky feeders
Evaluate each fish’s behaviour. Attempt a variety of foods and watch their reactions to each type. Certain specimens will only be attracted to certain sizes, so offer variety with consideration to size of mouth. Some good marine foods include:
Mysis: Frozen Mysis are a staple marine food. They offer high protein and fatty acids. Live Mysis shrimp can be extremely effective in eliciting feeding responses, but can be difficult to find locally.
Brineshrimp: Both frozen and live brineshrimp can be alluring to fish. As live brineshrimp (Artemia salina) age, their nutritional value drops rapidly. Baby brineshrimp are extremely nutritious and often accepted by zooplankton feeders like anthias.
Adult brine offer little nutritional value, but their swimming motion can be used to wean fish on to other foods. Try feeding adult brineshrimp a food supplement like Selcon. This will gut-load the shrimp and ensure your fish get some nutritional benefits.
Dried seaweed: Also known as Nori, dried seaweeds are a terrific food source for herbivores and omnivores. Try attaching the dried sheets to live rock rubble with rubber bands. Once the fish begins eating the algae, it can then be used on algae clips for easier daily feeding.
Live algae: Like dried seaweed, live algaes can entice herbivores and omnivores. Red Gracilaria spp. algae, known as Ogo, is a great starter food.
Blackworms: Few butterflyfish (Chaetodontidae) and angelfish (Pomacanthidae) can resist the wiggling and writhing motion of blackworms.
These once had a bad reputation for introducing disease, but this issue has since been resolved. Keep them in a container with fresh water inside the refrigerator and change the water daily.
Minced and chopped seafood: Clams, squid, shrimp and scallops are all healthy menu items and their strong smells can trigger feeding responses. Try slicing the meats in various sizes.
If a fish begins eating one of the seafood meats, soak new foods in the juice of that meat. The smell can help persuade a fish to try a new type of food.
Clam on the half shell: Omnivores like angelfish will often dine on presented clams. Buy them fresh, with no preservatives, and rinse thoroughly with RO/DI water. They can be cracked open to allow access to the meat, or split in half—hence the name. Remove uneaten food to prevent pollution.
Live foods can be offered as a temporary substitute to prepared foods. They include:
Copepods: Live planktonic feeds like copepods were once reserved for public aquariums. Today, they can be purchased in a bottle. Although costly, they can be fed to extremely picky zooplankton feeders like anthias.
Coral: With the success of captive coral propagation, we can offer live captive- bred corals to sustain fish in the short term. Soft corals like Xenia and zoanthids are rapid growers and are often grazed on by angelfish and butterflies.
This article was first published in the November 2009 issue of Practical Fishkeeping. It may not be reproduced without written permission.