If fish are not eating well or just acting different most hobbyists pick up on it quite rapidly. There are two very distinct types of “not eating”. Cichlids such as Oscars are prone to stop eating seemingly just for spite. They can go for weeks without eating, then start eating again with gusto, apparently perfectly healthy. They often do this if their food is switched.
Then there is where a disease has caused a blockage of the intestines. This is a whole different ballgame. Fish with intestinal blockages are, unfortunately, very difficult to treat, and most often will die even with the most aggressive treatments.
Necropsies on fish which have died with “no eating” or “food spitting” show the following incidence:
- 30% have “hexamita” (treat with metronidazole and Epsom salts)
- 20% have capillaria (treat with Fenbendazole or Levamisole)
- 20% have bacterial infections (treat with antibiotic)
- 20% have environmental mycobacteriosis (add lots of filtration)
- 10% have no apparent pathogen
Other symptoms such as hollow belly and bloat also have this “multifactorial etiology” and, like “not eating”, need to be treated with what is basically a shotgun approach with multiple medications.
If the fish is just “off” or acting funny but still eating a little the fish should be isolated in a bare bottom hospital tank and the following food added:
Make a concentrated solution of Epsom salts (magnesium sulfate) (takes time to dissolve), two tablespoons to a cup of water. Better yet buy magnesium citrate solution from your local pharmacy (it’s like Epsom salts, a laxative) and use it just as is out of the bottle.
Buy over the internet (these are only what the author uses, there are lots of options listed below):
- SeaChem MetroPlex,
- Maracyn 2
Then make some medicated food. Heat 1/4 cup magnesium solution (two ounces or 58 milliliters, not a lot) in the microwave. Then blend one 1/4 ounce of plain animal derived gelatin (Knox gelatin, one envelope) into the hot solution with vigorous stirring. Take two tablespoons of dry commercial fish food (pellets or flake) and mix it with just a little of the hot solution/ gelatin mixture. Add hot solution/gelatin until you get a paste like consistency. If it gets too watery just add more food.
Then add roughly 1/16 teaspoon (a 1% to 2% addition) of each of the three medications to the mud. Mix and mash the whole mass thoroughly. Spread it out into a pancake about 1/8th inch (3 mm) thick on a plastic film or a plate. Then put in the refrigerator. If you plan on keeping it for more than two weeks put it in a small plastic bag and freeze.
Feed it to your fish for one month. Note while the fish won’t eat it like they normally do, they typically will eat some if you just leave it in the tank. Note that the exact amount of medication which goes into the food is not very important. Antibiotics can be overdosed pretty much with abandon as they are only toxic in large doses over a period of months.
The treatment for “not eating” and/or “food spitting” has some options:
- metronidazole, alias metro’ options include API General Cure, SeaChem MetroPlex simply mixed into the food, or Hikari Metro Plus food or New Life Spectrum Hex-Shield food
- Fenbendazole (Safeguard for dogs, and several livestock dewormers) can be replaced with Levamisole (Amazon, subaquaria .com and Valleyvet .com, Agrilabs Prohibit Soluble Drench Powder and DURVET Levamed Soluble Drench Powder Dewormer). Other medications supposedly effective against roundworms are Pyrantel Pamoate, Flubendazole (Kusuri Wormer Plus) and Piperazine.
- There are several effective broad spectrum antibiotics, including Midland Vet Service Aqua-Mox, VetDepot Amoxicillin, Fishbiotic Ampicillin, Seachem Kanaplex, Mardel Maracyn 2.
Note the directions with most aquarium medications tell one to put large amounts of the medication into the aquarium’s water. This is a huge profit driven scam perpetuated by suppliers of aquarium medications. Fish don’t drink! And they also don’t absorb medications through their skin or gills. This controversial topic is covered in this link:
Giving Medication by Pipetting
If the fish stop eating altogether things get a little dicey. If fish haven’t eaten in a week one can do the following:
- Make up a solution of one fourth teaspoon each of Metroplex, Fenbendazole and Maracyn 2 in four tablespoons of magnesium solution (two tablespoons Epsom salts per cup of water).
- Enlist the help of another person
- Net the fish out of the tank one by one into a wet towel.
- With the other person holding the fish pry open the mouth of the fish with a plastic 1 milliliter pipette filled with the medicine solution.
- Put the tip of the pipette deep into the throat of the fish and squirt some of the medicine solution into the fish. A large fish might take a milliliter while a small fish might only take a tenth of that,
- Release back into the tank
This is a drastic solution many are uncomfortable with, but if the fish aren’t eating they will start dying, not because of starvation but because of the pathogen inside them.
The Shallow Bath Method
There is one alternative to the pipetting method. Take a flat container like a cake pan and fill it with tank water to a depth of roughly half the body height of the fish (typically about one quart of water). Buy Metroplex, Thomas Labs Fish Bendazole and Maracyn 2 (or Kanaplex). Add the amount recommended for 10 gallons of water by the medication directions (if no directions just do one quarter teaspoon) and two cups of Epsom salts per quart to the shallow water and mix well. Put the fish in the resulting soup and allow it to flop around and gasp for five minutes. Do this twice a day.
There is a good chance the fish will swallow significant quantities of medication during this bath routine.
This technique is based on the few studies which have shown medications to be effective “mixed into the water”. When one examines these studies one finds the researchers actually studied the fish with concentrated baths for short duration’s, not adding it to the water the fish was living in. The fish in these baths could not swim and were typically gasping and throwing themselves around. This allows some medication to go down the fish’s gullet.
The three big pathogens which cause not eating are covered in the following links:
The symptom of not eating is often accompanied by another symptom. These symptoms are covered separately in these articles: