So Frustrating.

[Munroco]

Just been watching my cardinals spawn in my community tank. Would really liked to have saved some eggs but couldn't think how

 

[MattTHEFISHMANROOKIE]

Marbles?That works for danios. Breeder Box?

 

[fluttermoth]

The trouble with many tetras is that their eggs and newly hatched fry are light sensitive, so they need complete darkness to hatch, and they also need microscopic foods, once they're free swimming.
 
They are breedable, but you need a separate tank to do it; one with very soft water and a thick layer of peat and leaf litter on the base. You condition the females in there, then add the males late in the evening. Paradoxically, it's light hitting the fish that induces them to spawn, so you have to be there next morning to watch them spawn, take the adults out and cover the tank up.
 
In the wild, the backwaters they live in are so thick with organics, leaves, branches etc, that the eggs sink right down into it and don't get any light, and it provides the microflora and fauna for the fry to feed on.
 
The water is also extremely soft and acidic; these fish have been recorded at pH levels of 4.5 and, while you can keep them in slightly harder, more neutral water, you really need to replicate the wild conditions for breeding.
 
For such cheap, common fish, neons and cardinals are a real challenge to breed!