Oto catfish

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Aquarium Advice Regular
Jul 25, 2022

I have several oto catfish and other louches in a well established cycled tank. Everything has been fine for many months but recently found one oto catfish very thin and not eatlng like the others ( who all have fat bellies ) . I've seen this oto being chased by another but don't know if this is just playful chase, mating behavior or other harmless activity or bullying? I've tried isolating this oto in a breeding box and given it alot of different foods but he seems uninterested in eating any. Any advice?
I'm only a little over three years into the hobby, so I don't have an answer for everything. Is there a possibility your oto that isn't eating could be a SAE or CAE. Where I get my otos (lfs) sometimes the CAE and SAE get into their tank. Usually my lfs catches this, but if it is a different species that requires a shoal, it would make sense. Really the only thing I could think of off top and only because it recently happened to me.
I don't think requiring a shoal is the issue since I've had the oto catfish for months and he had no issues eatlng before. It is onlt recently he has not been eating.
If the fish is losing weight while the others are gaining or holding weight, then it probably has intestinal worms.

Intestinal Worms like tapeworm and threadworms cause the fish to lose weight, continue eating and swimming normally, and do a stringy white poop. Fish can do this for months and not be too badly affected. In some cases, fish with a bad worm infestation will actually gain weight and get fat and look like a pregnant guppy. This is due to the huge number of worms inside the fish.

Livebearers like guppies, mollies, swordtails & platies are regularly infected with gill flukes and intestinal worms. If the fish are still eating well but losing weight, then worms is the most likely cause.

You can use Praziquantel to treat tapeworm and gill flukes. And use Levamisole to treat thread/ round worms. If you can't find these medications, look for Flubendazole, which treats both lots of worms.

In the UK look for:
eSHa gdex contains praziquantel that treats tapeworm and gill flukes.
eSHa-ndx contains levamisole and treats thread/ round worms.
NT Labs Anti-fluke and Wormer contains flubendazole.
Kusuri wormer plus (contains flubendazole) - sold mainly for discus, comes as a powder which is quite hard to dose in smaller tanks
Sera nematol (contains emamectin)

Remove carbon from filters before treatment and increase aeration/ surface turbulence to maximise oxygen levels in the water.

You treat the fish once a week for 4 weeks. The first treatment will kill any worms in the fish. The second, third and forth treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.

Treat every fish tank in the house at the same time to prevent cross contamination.

You do a 75% water change and complete gravel clean 24-48 hours after treatment. Clean the filter 24 hours after treatment too.

Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.

The water changes will remove most of the medication so you don't overdose the fish the next time you treat them. The gravel cleaning will suck out any worms and eggs that have been expelled by the fish. Repeating the treatment for 3-4 doses at weekly intervals will kill any worms that hatch from eggs. At the end of the treatment you will have healthier fish. :)
Hello Colin, I did check the poop but it wasn't white but the standard grey/black colour. The loach seems to ignore all food I give him but sometimes see him sucking on walls of breeding box.
Hello Colin, I checked my local fish store's website but did not find any of the medications you lised. However I didn't expect them to list everything so I will personally pop by tomorrow and see what they have in stock. You mentioned 2 groups of sicknesses and medication to treat. If I don't find a medication to cure both which group of sicknesses should I pryoratize first?
Thread/ round worms are more common than tapeworm (flat worms) so I would treat for round worms first.

Levamisole will treat round worms.

Flubendazole will treat round and tape worms.
Hi, I managed to get NT labs Anti-Fluke and Wormer and I hope it fixes things.

I also tried feeding the oto catfish tiny pieces of garlic, but so far he seems uninterested
Otocinclus catfish are specialised feeders that prefer algae, driftwood and biofilm. Some learn to take other types of fish food but getting them to eat garlic is unlikely to happen.
Update : I released the oto catfish back into the main tank after the 1st treatment. He seemed to have much more energy and immediately started feeding off the algae on the aquarium glass. At the end of day2 I did the water change. I will repeat the process as instructed to max 4 weeks and hopefully everything will be fine.
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