Aggressive Danios?

[enchanted]

I have 6 Danios, probably pearl/zebra mix from the looks of them.

I caught them killing a guppy today after I found one badly injured when I returned from being out.

The damage and everything is exactly what has happened to previous guppys and all guppys recently have been hiding in a corner of the 55 Gallon.

I also noticed my Corys hiding.

After catching and removing the Danios to the 30 Gallon my corys are back out, but the guppys are still skittish.

Has anyone dealt with this before? It seems the Danios decided it was their tank, although it was big enough for all. They were bullying all the other fish around.

 

[Tempestuousfury]

Not exactly sure why they made a group effort out of it. Normally it's one bully and they attack one another when kept in groups. The only thing I can suggest is placing them with more danios and fast fish taht can get away from them.

Perhaps an even more aggressive fish, such as a gorup of tiger barbs, so they learn to not attack other fish?

 

[enchanted]

Currently I have them in a seperate 30 Gallon with 8 "Feeder" Danios I bought today to cycle that tank.

I saw two right next to the one that was attacking. I'm not sure if any others were involved, but 6+ guppies later I'm not asking questions. I just moved them. I haven't decided whether to bring up a seperate tank for them w/ other aggressive fish, take them to the LFS, or leave them in the tank after its cycled and I add the puffer... If the tank was cycled right now, I'm angry enough that they would be in there with the puffer. But, they have about 6 weeks of time for me to cool down.

 

[Lateral Line]

I've found Zebra Danios to be quite nippy when a trailing fin is about. Normally if you keep enough of them, their aggression is worked out on each other, but a trailing fin is a trailing fin...

 

[enchanted]

What do you mean by "Trailing Fin"? I've never heard that term.

 

[wetwetwet]

Any long finned species - have a tasty fin trailing behind them - guppies being the perfect example




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[The-Wolf]

I have 6 Danios, probably pearl/zebra mix from the looks of them.

I caught them killing a guppy today after I found one badly injured when I returned from being out.

The damage and everything is exactly what has happened to previous guppys and all guppys recently have been hiding in a corner of the 55 Gallon.

I also noticed my Corys hiding.

After catching and removing the Danios to the 30 Gallon my corys are back out, but the guppys are still skittish.

Has anyone dealt with this before? It seems the Danios decided it was their tank, although it was big enough for all. They were bullying all the other fish around.

This, to me, sounds like they have been weeding out sick or injured fish.
They(guppies) may appear perfectly fine to you and me, but to the danios
they may have sensed someting that we couldn't, and then took the appropriate action. It just seems to me to be the natural way most animals deal the the, no so strongest, so why not fish?
Any way this is pure speculation and I have no evidance to back this up , but it makes sense, as theories go.

 

[enchanted]

Being a smaller fish if the Danios decided they were part of the school that is feasible.

Although no matter, I can't put them back in that tank.

I haven't decided what I am going to do with them yet. Right now I have the 6 large ones and 8 tiny ones (about 1/2") in the 30G cycling it.

I bought the 8 1/2" ones to cycle that tank.