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Mean Fish

PostPosted: Fri Oct 13, 2017 5:18 pm
by Photoman
I have a Yo Yo Loach I bought when it was small. Well, he or she is 3 inches and is a mean fish. It chases my Angels and swordtails. I think I have him for cleaning algae. I could bring him to the store. But if he is mean in my tank, he'll be mean in another tank. I guess if he is in a tank of large fish he might have met his match. What do you do with mean fish? :think: :shrug: :tomato:

Re: Mean Fish

PostPosted: Fri Oct 13, 2017 9:37 pm
by Diana
Some Loaches can be more aggressive than average. IME Yoyos are rather high on the list. Not as aggressive as most Cichlids or some Gouramis, though.

Yoyos are social. Keeping them in a group helps them to keep this aggression among themselves. Keeping a single is pretty bad.

I do not know if a fish (any species) that is mean in your tank would be mean in another tank. Here are some things to take into consideration.

1) Species. Each fish is an individual, but most individuals fall within a range that is typical for their species, like a bell curve. There will be unusual fish within a group that falls outside the norm for that species. I have kept fish in groups (schooling or similar social types) and seen the extreme ends of the bell curve. One fish that is simply a bully toward the others in the tank.

2) Other fish in the tank. Whether they are the same species or different species, they may help calm the situation, or may become the target. Do not mix fish that are much more shy with more aggressive fish.

3) Age. If the fish are the same species, but juveniles, they may get more aggressive as they mature, often having something to do with sexual maturity- staking out a territory, selecting mates, defending a nest and young... (Of course the details depend on the species) I have kept several Angels in a tank while they were young they were fine, but when they matured 2 of them paired up and claimed the whole tank. The other Angels were chased into a corner until I got them out of the tank.

3) Order of being placed in the tank. When you change the tank decor, or get fish for a new set up, start with the calmer, more peaceful fish. Add the potentially most aggressive fish last. If you have the facilities to hold the fish for a day or two, then spread out the additions so the calmer fish will feel more at home by the time the more aggressive fish are added. Fish (and most other animals) are more bold on their own territory. The first fish into the tank become the bosses. Fish added later either have to get along with them or be removed. Or get more aggressive and take over the tank.

4) Size of the tank. Different species seem to need different amounts of tank space to feel comfortable. The same pair of Angels that totally took over a 36" long tank (a tall 'display' tank with 45 gallons) claimed only about 18" long space in a tank 6' long. Aggressive fish in the 6' long tank (Jewel Cichlids and a 3-Spot Gourami) could go anywhere they wanted, except for the end of the tank the breeding angels claimed. On the other hand, the Gourami tried to claim the whole tank, and chased only other Gouramis, but chased them to death (I could not catch them). But he gave way when the Angels were breeding.

Anyway, if a fish is too aggressive for your set up you really have only a few choices:
1) Keep the fish and alter the set up to suit the fish. Perhaps more of the same species would help? Remove the target fish? Different decor, perhaps a few more caves or wood arches for the Yoyo to claim?
2) Move the aggressive fish to another tank, either in your house or a store, or another fish keeper.

Do not maintain a set up where one fish is terrorizing the other fish. Not fair to the other fish.