Are danios mean?

[Jacquelyn klonoski]

I am new to the tank, bit was really excited to start learning more about my fish and the tank. My fiance got me a small tank with two tetras and one green danio.
My danio would swim about the tank, never just chillin. When I came home from work the two tetras where dead and the danio was fine.
My friend had surprised me and got me two more dani,1 blue and 1pink.
When I put them in they swam about then the green one started chasing them. The next day both new danios where dead and the green one is still fine.

I don't have the slightest idea what to do. My fiance thinks the green danio is attacking the other fish. Help?

 

[FreshyFresh]

I would suspect a water quality issue as being the cause. Do you have a means to measure for ammonia, nitrite and nitrate in PPM? You need an API master test kit for this.

 

[irishspy]

I've never known danios to be mean, though I'm more familiar with zebras than the green variety. They do like to chase each other, however, and, if there are too few in the tank, they may chase other fish. Like FreshyFresh , I'd suspect a water quality problem.

 

[myswtsins]

Danios like a lot of fish will show minor "aggression" from time to time just to play or maybe establish a pecking order, all is usually harmless to other fish. They are better in a group so they spread that play around and don't over stress 1 or 2 fish. But before you go adding more fish....

Is this a new setup? Have you let the tank go through it's nitrogen cycle? What are your water parameters (ph, gh, kh, ammonia, nitrite, nitrate, temp...)? What size tank? Etc. The more info the better we can help you.

Danios in general are very hardy fish, the glofish variety seem just as hardy. If this is a non cycled tank it is possible the original green danio is inherently tougher then the tetras and better adapted to your tank conditions then the new ones.

Just for your personal information, glofish are genetically modified. Some people don't know that and don't like it, to each his own though. Just letting you know.

 

[FreshyFresh]

I love danios. They do live a life of total chaos, but I find them entertaining and smart little buggers.

I've got a single zebra danio in one of my 55s. I started with 4 of them over 3yrs ago and 3 have disappeared one by one without a trace oddly enough. Disturbingly enough, I may have tossed them out with water change water because they love to get right in you business during water changes. The lone ZD zips around happily, not bothering anyone and I'm CAREFUL not to bail him out of the tank on WC day.

I also have 6 celestial pearl danios in my 29. I've had them for a little over 2yrs. Started with 7, but lost one (found dead) some months ago. They're fascinating and beautiful little things. They're very chaotic as well, but will swarm the glass to see you.

 

[tanker]

Danios are hyper active, but not mean. They also do better in large groups, and by itself, it is probably annoying the others. The stress from the danio maybe contributing to the death, but not the cause. You will first need more danios.

 

[alan01230]

You have an ammonia spike. One green danio is not capable of killing a fish its size in a few days. They chase and get chased thats what they do but you need to take a sample of your water to a fish store and have them check it for you. Keep us posted