Angelika

It is the last remaining danio I have and I dont want to buy any more. This one is a survivor, it went missing for a week and came out during a water change after it had gotten into the filter system for that week and it was fat and happy...
I dont know whether his behaviour is because he needs more of his fish to school with, but as Im not going to get any more I am going to have to figure out what to do...

I had him in the 20 gal: I was doing my daily sit and watch my fish and I noticed that the danio was hounding one of the young albino corys. The cory was swimming all over the place like they do and bumping it and chasing it around was the danio....it was clear that the cory was trying to get away but it wasnt being very successful.

So I thought... mmmm.... OK Mr Danio you can go into the 55 gal with Hannable my angel, and the rest of the crew..... this tank has been great, no lost fish, no stressed fish, and the different species all hang together... its very active and again Ive had no problems....

I have in the 55 gal
1 angel
7 hatchet
7 long finned minor tetras
4 corys
5 otttos
1 cucko catfish


As soon as I put the danio in there, he grouped himself primarily with the hatchets....
This morning, I wake up and my peaceful tank has 1 hatchet that has literally his has had 1 of his tail fins chewed off and part of his flying fins (dont know the names of them) Would a danio do this I have had zero probs in this tank, not one at all...up until this morning finding my poor hatchet has lost half his tail.

So I scooped out the danio and put him into the 12 gal with the 3 platies.... I dont know what else to do.....

acidpope

"Behavioral problems with this fish, such as fin nipping, can usually be attributed to not having enough of these schooling fish in your tank. To prevent this fin nipping behavior try to keep a school of 6 or more in your tank."

That's from the fishlore page on the zebra danio fish. Like alot of other schooling fish, when they aren't kept in groups they become either withdrawn or fin nippers. I'd say your danio munched on your hatchet, since all signs point to that.

You can either get him a few more fish which is pretty much the only way you'll curb this behavoir, or find a LFS or someone else who'll take it off your hands.

Angelika

yeah I thought Id have to find him a home as I really dont want any more danios..... I guessed this was the reason. thanks for answering.

ShaynaB

Yeah...

I had zebra danios that nipped a cory cat's tail fin all the way to the nub before I'd gotten the chance to see it. (Literally, from the time I was at work to the time I came back.)

The cute little demon fishes were back at the LFS that night.

I had a school of them and they still did it. I'm guessing it's cause they thought the cory was another danio and were trying to get him to play. They would chase each other like it was a game of tag.

Angelika

You know shayna, that is exactly where the hatchets tail was nipped too.... I was shocked, right down to the nub..... well the danio went back to the LFS where I bought it. I told them that I had purchased it with 7 others and over time they have all died, and this big fat happy cat was OK but now nipping his tank buddies due to being a solo danio and I was bringing it back... so I signed a release form and back it went...