Aggressive / stressed male swordtail

[Vorpal]

Hi everyone,

We started our swordtail family with 3 fish, bought from a pet shop. I have since discovered that they don't treat their fish very well, and stopped spending my money there. 2 of our 3 original fish have died. The one that remains has been a bit of a problem. Any time I put him in with other swordtails of either sex, he either becomes aggressive with them and harrasses them all the time, or he gets stressed and sick, or both. I suspect his behaviour is the result of being raised in an overcrowded tank with poor water quality.

He's fine when he's on his own, but we don't have the tank space for that.

We have a 120 L tank with 7 corydoras sterbai, 3 mature swordtails, and 4 young ones, a 60 L with Mr. aggressive in it, and a 30 L hospital / breeding tank with a couple of fry.

I can move Mr. aggressive to the hospital / breeding tank, then I can put female swordtails in one tank and the rest of the males in another, but I lose the use of the hospital / breeding tank. We can potentially get another tank. My son wants to, but it's a lot of work, which is a problem for me.

So, my questions are:
Is there some way to calm down Mr. aggressive?
Are there any solutions to the problem I haven't thought of?
If we do get another tank, or leave him in the 60 L, are there some other tank mates I can put in with him that are unlikely to be a problem? He seems fine with the corys, but that might be a bit much for the 60 L tank?

 

[Colin_T]

Male livebearers (guppies, mollies, platies, swordtials) are all territorial to some degree. They chase smaller males away so they can breed with any females in the area. You probably just have a male that is more grumpy than most. If you are not particularly fond of him then trade him in at the petshop and get a few others.

If you like him a lot and want to keep him, put him in the 60 litre tank with some peaceful barbs like ruby or golden barbs. These can tolerate similar water to the swordtail and are generally pretty resilient so if the swordtail gets grumpy with them they should be able to hold their own. If they get picked on then stick the male swordtail on his own.
If you do get barbs, have a group of 6-10 of each species so they keep each other occupied.

If you plan on keeping livebearers try to keep all males or all females and get fish that are similar sized so no particular fish has a size advantage over the others.

 

[Vorpal]

They are my son's fish & he loves all of the fish.
Not only would he be unwilling to trade in Mr. Aggressive, but I don't think I would, either. I don't think he's last long because he has developed what seem to be dropsy symptoms (bloated belly, raised scales) the last three times I've tried putting him in with other fish.

 

[Aesthetic-fish]

Hi, my guppy is quite aggressive to my platy as well. But luckily, my platy is a chill guy and he's fine with it. Anyways, to help u, you can try switching around the ornament design in your tank. But do keep in mind to do that in a fairly dim lit place, and try not to stress ur fish. Another method is time out, you put the aggressive fish in a small but not cramped space with a few ornaments, leave it in overnight as long as it doesn't show any stress. Lastly, if ur tank isn't heavily decorated like mine, than u can try adding some more hiding spaces. Good luck!!!

 

[Byron]

Keeping fish in too small a tank is not putting the fish first. A 60 liter (15 gallon) is not large enough for one swordtail, and not large enough for a group of barbs (Black Ruby and Golden were suggested somewhere). So this is not the solution.

There is no humane way to reduce aggression in a fish. Putting it in a too small tank is cruel to the fish and likely to make it even more aggressive. Sometimes the fish become so stressed they do lose their aggression but this is not because they are "learning" but because they are suffering and have no way to respond except withdrawing and slowly weakening to death.

This is a scientific hobby, and a large part of it is learning. And because we are dealing with nature, we have limits and have to accept these. Resolving issues can sometimes be heart-wrenching, but it is still necessary or the fish suffer even more.

 

[Vorpal]

TBH, he does not seem stressed in the 60L He seems happy there. He does seem stressed in any tank with other swordtails. So, that's the solution for the time being.

I was, you may note, also asking about if we get another tank. I am aware that the 60L at least does not have space for a group of barbs. And also aware that we have capacity issues at the moment.

What would you suggest is the minimum tank size for a mature male swordtail?

p.s. my son has saved up money for a used tank. He's not quite there, yet, but I can help him a little, if needed.

 

[Byron]

TBH, he does not seem stressed in the 60L He seems happy there. He does seem stressed in any tank with other swordtails. So, that's the solution for the time being.

I was, you may note, also asking about if we get another tank. I am aware that the 60L at least does not have space for a group of barbs. And also aware that we have capacity issues at the moment.

What would you suggest is the minimum tank size for a mature male swordtail?

p.s. my son has saved up money for a used tank. He's not quite there, yet, but I can help him a little, if needed.

You cannot possibly know if a fish is happy or not. And fish can be under stress with no external visible signs, until it is too late. But regardless of those facts, the swordtail on his own in the 60 liter is the better option under the circumstances.

As an adult swordtails range from four to as large as six inches (10 to 15 cm); in aquaria 4-5 inches (10 to 13 cm) is normal, with females slightly larger than males. You will commonly find them from two to three inches in pet shops. At that size they are generally six to nine months old.

A tank with a length of 30 inches (76 cm) is minimum. This would include a 20g long or a 29g standard. Given these have the same footprint (length and width) the additional space in the higher 29g is worth considering as it allows more options. Filter and heater would be much the same in either tank.

 

[Essjay]

A tank with a length of 30 inches (45 cm) is minimum

Just a slight correction - 30 inches is 76 cm not 45 (45 cm is 18 inches)

 

[Byron]

Just a slight correction - 30 inches is 76 cm not 45 (45 cm is 18 inches)

Yes...that's what happens when I do math in my head.

Thanks essjay, I corrected the post so it wouldn't confuse.

 

[Vorpal]

You cannot possibly know if a fish is happy or not. And fish can be under stress with no external visible signs, until it is too late. But regardless of those facts, the swordtail on his own in the 60 liter is the better option under the circumstances.

I did say *seems* happy.
While I cannot know if he is happy, it is possible to kind of get to know a fish, in a way, and he certainly displays some personality. He also displays obvious symptoms of stress and becomes poorly when in the company of other swordtails. This seems to have become worse with each attempt. He does not display them when he isn't in with other fish, and he currently seems healthy. Our last attempt to put the (3) males together in the 120L (as recommended by another thread on here) took him several weeks to recover from.

p.s. we've tried things like rearranging the plants and decorations

 

[FishGuest5123]

In betta sororities it is common to take an aggressive female and put her in a breeders net for “ time out” when first starting the sorority. I know it sounds crazy but after one or 2 times in the box they settle down. This gives all the fish an opportunity to get use to the new fish without harm. Not sure if it would work with a fish already established in the tank.