territorial Rainbow Fish, is this ok??

[butterfly]

I am a complete beginner. I bought my 22g tank at Christmas and completed a fishless cycle 2 weeks ago. I first added 3 otos and a week later a shoal of 5 Neon Rainbow Fish (Melanotaenia praecox) 3 males and 2 females. I asked the LFS for the smallest fish but also all of a similar size.
The Rainbows were added to the tank 4 days ago and after an initial settling in day or two, the largest male seems to be bullying the other two males whenever they stray into his 'territory' (if that is what it is). He has not hurt any of them, he just opens his mouth and lifts his fins to frighten them and he is only doing this with the other male Rainbows. He does not bother with the Otos.
I would not be so concerned with this behaviour, but his territory would appear to be the entire front part of the tank. This means that the other males gather at the side and wait until the big male isn't looking before they venture across the tank for a little swim.
I am worried that, although this may be entirely natural behaviour in the wild, it will not allow the group to be happy and stress free in a tank environment.

Can anyone advise what I should do please. Is this acceptable behaviour in an aquarium (the LFS told me I could return an agressive fish)? Could I be doing something to cause the bullying?

 

[Toadfish]

well the first problem might be the male female ratio. I would suggest either go with a 1:1 or a 1:2 ratio. More males than females means that one of the males doesn't get a partner (possibly even two males depending on how greedy the 3rd male is). The kind of aggression you are describing is usually assaciated with breeding. My question for you is how does the dominant male treat the females in the tank? Because likely what is hapening is he is getting protective over "his" females because he wants to breed with them.

 

[butterfly]

Thanks Toadfish.

I've not seen any heavy agression between the big male and the other males when the females are around, but I have only had the group four days. Currently, the big male sits in the middle of the front of the tank and if either of the other two males trys to pass, he chases them away.

I will keep watching and see if I notice anything when the group is more together. I guess one option open to me would be to change the big male for another 2 females (1:2); do you think my tank is big enough for one more Rainbowfish?

At the end of the day, do you think I should be concerned about behaviour like this and try to change things?

 

[Toadfish]

I'd only be concerned if there is danage being done to the fins, eyes, or the other two males are getting skinny because of lack of food.

 

[parker313]

If Praecox are the dwarf rainbows I'm thinking about, you could easily add in another fish. If you wanted, you could even just keep the fish you have and add in 2 more females. Rainbows are schooling fish so sometimes the answer is just to make the school bigger to spread out the aggression, especially once you get an optimal m:f ratio if you're still having problems.

 

[butterfly]

Parker313, thanks. It's a good thought, especially since it allows me to keep the fish I already have (and they are great fish!). I have no plans for any other fish species, so if a couple more female Praecox takes me to full stock, so be it.

 

[butterfly]

Adding this post just for information .....

I did buy two more females and it worked a treat! I now have a group of peaceful, happily schooling Rainbow fish.

 

[Raechal]

Adding this post just for information .....

I did buy two more females and it worked a treat! I now have a group of peaceful, happily schooling Rainbow fish.

Great to hear!

 

[parker313]

YAY! I'm so glad it worked It's always nice to hear the good updates