Mystic54

My dad currently has 2 rainbows in a 35 gallon. Well recently I noticed that the larger of the two chases and even nips the side of the smaller one. Is this normal? I'm also not sure how to sex rainbows. I'm not sure if we have a male to male pair, female to female pair, or male to female pair.

Jaysee

Well, for starters, rainbows are highly schooling fish and ought to be kept in larger numbers. Also, depending on the species, a 35 gallon tank (30" long?) may not be big enough.

Mystic54

I don't have the time to take pictures right now but the rainbows look like the ones in the 6th post in this thread Rainbow Fish Photos

Toddnbecka

Rainbows are best kept in at least a 4' (55 or 75 gallon) tank in groups, 3m/2f being the minimum size/ratio.

Jaysee

Looks like an australian rainbow. If it is, they can reach more than 5 inches and need at least a 4' tank, like T&B said.

Dwarf neon rainbows are better suited to 30" tanks.

Mystic54

I guess that decision would be up to my father if he wanted to get a bigger tank or not. He already has a 55, but it has max amount of fish in it now since we added some BN plecos. I will let him know about the size they can potentially reach. Although, they are both about 3-4 inches now. My main concern is the larger one picking on the smaller one. And after reading some posts I think we have a male to female pair.

Jaysee

Try adding another female

aquarist48

Hello Mystic. Sorry to hear you're rainbows are misbehaving. I had the same issues a while back with the same fish. One killed the other. Then the surviving one started chasing my Silver dollars all over the place. I had to remove it. Sounds like good advice above about the ratio M to F. Maybe it would help prevent the chasing issues.
Best of luck!
Ken

jprime84

I recently got a trio of boesemani rainbows as well. I have also noticed dominant behavior in the most colorful male (im assuming its a male). The boesemani rainbows can grow to around 3.5-4 inches, perhaps 4.5 inches for the big males.

Right now my fish are around 2.5-3 inches and the dominant fish is beginning to have his color come through. The other fish are duller in color. I am not sure, but I think I have a male with two females. First thing in the morning is when they get rough. I dont see a ton of nipping, but there is some chasing involved.

However, the fish arent cowering from him or anything, so I am just going to watch it for now. From what I read, their courting habits can be somewhat aggressive.

Jaysee

What you're seeing in the morning is spawning. They'll do it every day.

jprime84

I wish I could tell which was which sex. Mine have not had their colors come in all the way since the store. They are maybe a little over 2 inches long. They have yellow on their tails, with a few blue scales up front. There is a faint brownish line down their sides. Ill post pics when I can.