hello, my names Jackie im new to tropical fish had my tank 6 weeks and got 4 platies and 4 zebra danios after one week, one danio died but the others are fine, one platy had about 12 babys i managed to put 2 in a nursery but saw the others get eaten alive! then last night (28th)i saw a baby appear from behind some bogwood i am planning to get 2 catfish is this wise. Also im having problems with the nitrite it just wont go even though im doing 30 litre water changes every other day its a 180 litre tank rio 180, the amonia is at 0. can anyone give me advise. thank you.