Is there any way to tell if my fish will be aggressive?

Question

Another question about the Betta. Now that he's doing better (merrily swimming and darting around), my boyfriend and I are greatly enjoying the aquarium. We've been discussing putting some other fish in (possibly a couple Dalmatian Mollies), since he looks a little bored sometimes. Is there any way to tell how aggressive Ozzy (the Betta) will be?

I've stuck my finger into the tank a few times, and he just sits and stares at it from a distance for a few seconds before going back to what he was doing. I've heard suggestions of getting a feeder guppy and seeing how he responds to that, but I've also heard people say that guppies aren't good for these things, since they have the flowing tails.

Tank specs: 5 1/2 gallons, heated (currently between 80 and 81 F), filtered, water is conditioned.

Decor: Two plastic plants and a Buddha (because we couldn't pass it up), and looking into getting a floating vase for lucky bamboo.

Any suggestions?

Answer 1

It is possible for some Bettas to peacefully co-exist with other fish (although I've never had that set-up). A 5.5 gallon aquarium isn't very large. A lot of times when 2 or more fish of different species are put into an aquarium, the reason that it is able to work is that there is enough space and hiding places for each of them. If you think about it, in a 10 gal tank, two fish will cross paths only half as often as in a 5 gallon tank. In a 5 gallon tank, the fish will come into contact 4 x as often as they would in a 20 gal tank. Betta fish have always had a reputation as being aggressive toward other members of their own species, so definitely don't try that experiment!

To get some understanding of this, you could hold a mirror next to the cage to see how Ozzie reacts. But don't keep it there for too long or he could injure himself. Here is my suggestion. Get a 10 or 20 gal tank. With this you can try combining your betta with another type of fish. Keep in mind that whichever fish goes in first will claim the tank as its own, and from then on defend its territory. So put the least aggressive fish in first. A lot of fish are also more aggressive when they are the only fish of their species in a tank (normally schooling fish in nature). You could try putting 6 or so small schooling fish in the larger tank first. Letting them get used to the tank and then gradually acclimate the Betta before putting it into the tank along with them.

Keep your 5.5 gallon tank set up for a week or so, so you can just put the Betta back in it if the combination doesn't work out.

Other suggestions:

Don't get Cichlids, freshwater sharks, or any other fish that isn't considered to be a community fish  for your tank. Try moving around any aquarium decorations if you find that the fish are becoming too territorial. This hypothetically resets the lay of the tank and lets the fish designate new areas as theirs.

Hopefully you will get responses from people who have successfully put Bettas with other types of fish. I have not, so you can take or leave my suggestions as you see fit. Good Luck  

Answer 2

Don't get fish with long flowing tails as it will see hem as a rival male and will attack it. They should be fine with short finned shoaling fish. Maybe neons or zebra danios. Yeah well like i said anything that has short fins that won't be seen as a rival . Gorami's are good...

Answer 3

Well, have a backup tank to put the betta in if he is aggressive. Do not get very colorful fish that have long fins. African dwarf frogs make really good tankmates for bettas, as long as you keep the dwarf frog well fed on bloodworms he will not mess with the betta. (Sometimes dwarffrogs misteak a slow moving betta tail as a big worm, but this will not happen if they are well fed.=) )

Answer 4

I wouldn't put any other fish in a tank with a male betta. Once the betta feels threatened, it will attack the other fish, maybe try putting a box thank inside of a bigger tank, so it looks like they are all together but still, the betta is still seperate from the others.