Why have my otos gone into hiding?

[Gypsum]

I had six otocinclus but now five, as I pulled a dead one out of the tank this morning (poor wee guy). I've had them for about a month. I'm aware attrition rates are high with these guys, but their behaviour has changed over the past few days. They used to be out and about on the tank glass, the filter, assorted plants, but now they all hide on a plant in the most heavily planted corner. I haven't even seen them when the tank lights are off.

Water parameters are as follows: Ammonia, 0; Nitrite, 0; Nitrate, 0; Ph, 7.4. Water is soft, as Scotland doesn't have hard water anywhere.

Is there another fish in the tank that could be stressing them out? I have six rummynose tetras, four cherry barbs, five black phantom tetras, five false julii corys, one Bolivian ram, and one raphael catfish.

 

[Colin_T]

It sounds more like a water quality issue than stress from other fishes in the tank.

The only fish you have that might be an issue to them is the Raphael catfish, but if the fish are dying, then it's either a disease or water quality.

Have you got driftwood and algae in the tank for the Otocinclus to eat?
All suckermouth catfish need driftwood and algae and Otos have small stomachs and need a steady food source. If you don't have algae in the tank, increase the lighting times to encourage a bit of algae to grow on the glass.

You can put a plastic storage container outside in the sun and fill it with tap water. Add 1 level tablespoon of lawn or garden fertiliser per 20 litres of water. Put some smooth rocks and ornaments in the container and leave it to turn green. When the items are covered in algae you move 1 or 2 items into the tank and let the fish graze on it. When the items are relatively clean and free of algae, swap them for a couple more items in the storage container.

 

[FishGuest5123]

I agree that it sounds like a water quality issue. What are your water parameters?

 

[Colin_T]

Water parameters are as follows: Ammonia, 0; Nitrite, 0; Nitrate, 0; Ph, 7.4. Water is soft, as Scotland doesn't have hard water anywhere.

I know the water looks right but it still sounds like a water quality issue.

 

[Gypsum]

All other fish are bright and lively (including rummynoses, which are pretty sensitive to water quality). What else is there to test for? One of the otos never seemed 100% since getting it from the shop, but the others have only recently gone into hiding. They just stay in one corner, regardless of the lights being on or off. I'm concerned that they're not eating enough because they're not really leaving the one plant.

There's plenty of algae on the glass, the other plants, and a big driftwood log.

For argument's sake, let's rule out water quality -- could it be that they're being stressed by something, i.e. the raphael?

 

[Colin_T]

For argument's sake, let's rule out water quality -- could it be that they're being stressed by something, i.e. the raphael?

yes

 

[Byron]

I agree this could be a water issue, or the Rafael catfish. It could also be something else, like starvation.

Otos are wild caught, and from the time they are collected until they reach the store, they have no suitable food; many arrive next to dead from starvation. The store tank may or may not provide sufficient suitable food. When you get them home, if there is a source of common green algae or diatoms, they usually improve if they are not already weakened beyond hope. You say there is/was algae, so that may be true, but otos will not eat any algae--brush, beard, hair, etc, any of the "problem" algae--will be ignored. They must have common green algae (which naturally occurs in the biofilm on surfaces) or diatoms. Dried leaves can work too. Once they are settled, they often get used to prepared foods such as algae/kelp sinking disks, but in most cases they will ignore this initially so natural food is essential.

The Rafael catfish might be a problem. No mention is made of the tank size, or the Rafael's size, but this fish attains up to 8 inches (6 is common in an aquarium) and it will eat small fish especially at night when it is prowling and they are asleep. It needs at minimum a 4-foot length tank, and obviously carefully-selected tankmates.

 

[Gypsum]

Our raphael is 4" and the tank is 3ft. It's about four years old (we inherited it with the tank -- the previous owner was moving to Canada). She hasn't tried to eat any of her tankmates, and the others have got used to her. But the otos seemed to increasingly cower in one corner.

I shifted the otos into my unused 20g tank, along with some algae-covered plants and an ornament (and obviously running it with one of the filters from the big tank). The good news is that they seem a lot perkier and are swimming around. However, there isn't much algae in the tank. I know throwing them into a clean tank isn't ideal, but they couldn't stay where they were. I gave them an algae wafer and a slice of cucumber but they haven't eaten those.

Any tricks for encouraging them to eat?