I cycled it how the tank manufacturer said before putting any fish in, and the danios are shoaling fine and not bothering the resident goldfish at all thus far. 'Waiting until the damage is done' is really a 'seeing if something works before changing it' and I'm not sure what can be so bad about...
>nurglespuss
Thanks! It's been a couple of hours and I am happy to report that the resident goldfish has lost interest. If he starts to look too big for his tank, I'll invest in something larger. Same goes for if his fins look as if they've been nipped at.
That's a little worrying, but I've heard from a few people that goldfish grow to different sizes depending on their tank and that plenty of people keep goldfish in small tanks. Are you really sure about this?
About a month ago I set up a 35l/9gal tank and after beggining the cycle detailed in the instruction manual and generally sorting it all out, I introduced a common goldfish a little over 2". Today I bought 3 zebra danios and 2 leopard danios to join him, and I'm confident they're too big for the...