Should I replace .....

[lis]

I've had 4 White Cloud Mountain Minnows and 4 zebra danios in my tank for the last year. They all seem to shoal together, although one by one 3 of my zebra danios have died.

Now the last remaining danio swims about on his own ignoring the minnows. Should I replace the danios?

Thanks

Lisa

 

[black angel]

You need to find out why the other danios died first before getting more.
What size tank, ph, any results for ammonia, nitrite and nitrate?