Originally Posted by Byron
As mentioned in the profile, this is a shoaling fish, so they are best in small groups. Length is more important that volume, but in less than 4 feet I wouldn't either. A pair is fine if it is a mated pair (not all males accept all females, and vice-versa) but as these would spawn regularly this would make life in the tank difficult for the other fish. Then there is the issue of linear tetra being eaten by angelfish. Cardinals are linear, and many have had these disappear into angels. The disk-shaped tetra such as those in the Rosy clade of Hyphessobrycon (avoiding the fin-nippers) or the medium rasbora are better tankmates.
Yeah, the tank is about 40" long, so not quite four feet. I was under the impression that cardinals are okay since a lot of people seem to keep them together with no issues because of their size? A lot of people seem to keep rummynose with angels as well? Yes, when I mention pair, I meant a genuine mated pair... I have also been told I could grow out a group of 5 or 6 juveniles, and after a pair form, sell the other ones? What do you think about that theory?
Also, do you have any advice as to what I was asking about my cycle, as to whether clearing of 2ppm of ammonia within 15 -18 hours is okay, or if it really is true that I am not cycled until I can clear 2ppm of ammonia within 10-12 hours? And I mean clearing the ammonia within that amount of time for a week straight before adding fish, just to be sure.