Aggressive Male Shubunkin

[shunkinmom]

I have a shubunkin that appears to be constantly trying to mate for the last 2 months since I got him. I am a little concerned that he is stressing out the other fish. He won't even let them eat in peace.

We have had our pond for approx 15 years and I have never seen such persistent, aggressive behaviour. Should I "re-home" this fish? Our pond is quite small and there isn't much hope of the others escaping from this guy.

This sounds like a strange concern, but I can assure you it is quite legitimate.

[perplexed ponder]

Maybe a trial seperation? Do you have a tank he can have a time out in? He must be tired!

[shunkinmom]

Maybe a trial seperation? Do you have a tank he can have a time out in? He must be tired!

I don't have a safe tank to put him in. Last time I tried to separate a fish that I had promised to a friend, he did not make it through the night- even with a net over the round laundry basket sized bucket I had him in. Too many raccoons around here.

I guess that at this point I am curious to see if he ever slows down. The only time I have ever seen such compulsive behaviour was in a sick cat, who I was told had developed some sort of chemical inbalance in the brain due to all his medications. He developed a compulsion to chew and destroyed half the furniture in our house over a period of 2 or 3 days.

[ThornyGardener]

There are some fish that are 'disturbed'. Some are fin nippers, some are reclusive and never go near the others, some never leave the side of another, some are slime suckers and some have .

A few years ago I moved a new small 6" shusui koi from the quarantine tank to the main pond where for two months he persisted in sucking the slime coat off the much larger others. I was advised that this aberrant behavior is rare but can be lethal to other koi so he should be euthanized. Instead, I put him back in the basement quarantine with two veiltail goldies on which he never feasted. The following spring, I returned him to the pond as a test and he never did it again. 

Whether you try the timeout (but he will need a male companion), the rehoming or the clove oil dispatch, do try something for the safety of your other fish. With your small pond you dont want to be inundated with fry, especially those carrying the male's agressive gene.

Good luck!

[miguynmkoi]

Maybe my pond doesn't have many hiding spots for frys.  My fancy goldies seem to be "chasing" all the time from early Spring to late Summer.  Lots of eggs are deposited in the bunched anacharis area and after all the action it looks like buffet time. 

I have an aggressive female shub who chases other females amd males.  She's one of the bigger fish in the pond and makes like she owns the pond.  I could say that most of the offspring that survive the buffet do look like hers.

Hope time makes your guy shub slow down some....teenage hormones? 

[shunkinmom]

There are some fish that are 'disturbed'. Some are fin nippers, some are reclusive and never go near the others, some never leave the side of another, some are slime suckers and some have .

A few years ago I moved a new small 6" shusui koi from the quarantine tank to the main pond where for two months he persisted in sucking the slime coat off the much larger others. I was advised that this aberrant behavior is rare but can be lethal to other koi so he should be euthanized. Instead, I put him back in the basement quarantine with two veiltail goldies on which he never feasted. The following spring, I returned him to the pond as a test and he never did it again. 

Whether you try the timeout (but he will need a male companion), the rehoming or the clove oil dispatch, do try something for the safety of your other fish. With your small pond you dont want to be inundated with fry, especially those carrying the male's agressive gene.

Good luck!

Good heavens, I never considered fry who would inherit this gene. 


The place where I buy my fish has several very large ponds in the back, where they allow you to drop off your unwanted fish. (The owner swears that they do not re-sell them.) I think I am going to take this guy for a final car ride before I lose all my fish from stress. The poor girls cannot even eat in peace.

No, I don't think it is just teenage hormones because over the last two months I have never seen him when he was not bothering another fish. It is very bizarre. I won't tell you what we have nick-named him.

[perplexed ponder]

I never htought of the fry either! Yeah, the ponds behind the store sound like a good solution to me!