Fish Aggression and Tank Size

[jlnguyen74]

I've heard (or there's a theory) that big tank will help to reduce fish aggression, perhaps, someone thinks that with more space, fish will fight less for territory. However, my experience is quite contrary.

I keep 12 arowana in my 600gal tank. They fight daily, if not constantly. They even fight with the barramundi that is a foot bigger than them! Sometimes, there was one or two of them just single out one or two other arowana, and keep chasing and put them in a corner of the tank, and won't let them leave that corner. 3 weeks ago, I moved five of them to a 300gal tank that already has one arowana in it (new one.) Two of the five I moved are the ones that fight the most, the other 2 are the one that always got bullied into the corner, and one is a mild manner. For the past 3 weeks, I hardly see them fight, may be flaring at each other on the first few days, but there was no chasing or biting as when they were in the 600gal tank

When I kept my peacock bass in the 500gal tank last year, I always have hard time to introduce new fish, including new peacock bass, in the tank. Whether the new fish are same size or even bigger, have teeth or fang, they always got gang up and beaten badly, or killed over night by the group of peacock bass that have been in the tank. Early this year, I sold the 500gal tank, moved them to a 150gal tank, and 3 weeks ago, moved them to a 300gal tank (not the same 300gal tank that has arowana) I have no problem with introducing new peacock bass in the tank, when they were in the 150gal or in the 300gal.

I have two Aimara that I keep with the peacock bass. When they were in the 150gal tank, they hardly fight, each stay in the corner most of the time, and when they run it to each other, some flaring and a little nipping now and then, but nothing serious. I moved them to the 300gal with the peacock bass, and for the past 3 weeks, one (slightly bigger) keeps chasing the other, shred its tail and fin, gave it a slight cloudy eye, to the point I had to move the slightly small one into the other 300gal tank with the arowana last night.

The only change this fish experienced was tank size. Other than that, feeding schedule, water change schedule are still the same.

I'm interesting in hearing other member's experience, prefer first hand experience, not second hand experience, or "google" information

 

[Dloks]

kept 6 aro in a 150 did fine put them in a 210 lol all hell goes loose big scales everywhere, and never had luck putting any pbass in with a already dominate pbass in the tank, always ends up bullying the new tankmate to death or swallows it whole ahaha

 

[jlnguyen74]

kept 6 aro in a 150 did fine put them in a 210 lol all hell goes loose big scales everywhere, and never had luck putting any pbass in with a already dominate pbass in the tank, always ends up bullying the new tankmate to death or swallows it whole ahaha

Thanks for the info. I noticed that arowana do better in smaller tank. I kept five to seven of them in a 225gal few years ago, and they did fine. Once I moved them to the 600gal tank, all hell broke loose, too, even I added more arowana to the tank, and it didn't help.

 

[Dloks]

I always thought 'those' type of aros are communible and what nots

 

[smitty03281964]

That is why I always tell people that there is no definitive answer when it comes to fish keeping. In the case of the Pbass he had already claimed that tank and was not going to let anything else have a part of it. Now when you move fish from a smaller tank to a bigger tank fighting can break out because the fish are trying to establish territory in the new tank.

 

[Aqualoon]

That is why I always tell people that there is no definitive answer when it comes to fish keeping.

Exactly.

I see people that have Red Devils, Flowerhorns, Midas, etc. in community setups that do just fine. Yet others who can only keep these more aggressive types of fish in their own tank.

That's why I now tell people to go ahead and give it a try, but to make sure you have a backup plan in case things don't go how you want.

 

[jlnguyen74]

That is why I always tell people that there is no definitive answer when it comes to fish keeping.

That's the answer I got, when I asked several fish keepers back when I first started community setup. One respective member told me that he doesn't know what advice he should give, because he thinks that what may work in his tank, may not work in other tank, and vice versa.

 

[Water]

Theres a ton of factors that lead to aggression. For 1, overstocking your tank like you did a few years ago is asking for trouble. Moving new fish to a tank that already has an established group of fish and the new fish getting beat up. Thats nothing new. The fish that have been in your tank have established the tank as their territory and will not be very accepting of intruders. As for when you moved the Arowana into a bigger tank, they fought because they were fighting for territory. I believe firmly that the bigger the tank, the lesser chance of aggression issues, but theres always exceptions to everything. When it all comes down to it, it really depends on the fish themselves whether or not they want to be friendly or kill their tank mates.

 

[Nile Perch]

That's the answer I got, when I asked several fish keepers back when I first started community setup. One respective member told me that he doesn't know what advice he should give, because he thinks that what may work in his tank, may not work in other tank, and vice versa.

I would say the same. I've heard of exceptions of species that may not necessarily co-exist do so for many years. Regardless of anything a back up is a must.

 

[Jc1119]

I think as a general rule, a bigger tank should have less aggression, but there are alot of factors involved in trying to curb aggression. My experience is bigger is better but every bigger tank I've setup have had all stock introduced together or the most aggressive species was always introduced last ( and was the smallest fish in the mix) Often, I've had to move fish around and isolate a few, but generally the bigger the tank the less aggression I've had.

I just setup a 300 that houses 6 cichlids. 5 of these cichlids were in a 90 growout for about 4-5 months. Aggression started to become an issue between my Jd and smaller GT, so as an experiment I bought a larger Midas to introduce to the tank. Immediately, my Jd chilled out and all aggression stopped. It was an active tank and sometimes there were minor flare ups, but for the most part all was well. Midas ran the show and everyone got in line....

Now in the 300, all 5 cichlids and a Freddy are living aggression free. Fish are colored up and several of the girls are showing breeding signs. Now, I can't say it'll be this way forever, but I don't really even have minor issues. Ironically, with all the space in this tank, 3-4 of these fish insist on hanging out together and seem to be very relaxed around each other. Wherever my Midas hangs out is where you'll find the Jd, Freddy and a female con.

I think alot of this tanks territoriality issues have been curbed a bit because 1) all stock is 6" or less and 2) They were all introduced together. Now, that being said, I have a Festae that is only about 3" and is too small to join the group. Once this fish reaches about 5-6" I'm going to try to introduce it to the tank, but I'm expecting some issues at first. Most likely, I'll have to isolate some of the same sized fish while I attempt the introduction, but even then, it's possible it won't work the way I want it to. Guess time will tell.