u/Apprehensive-Ebb8422

The tank has been running for about 7-8 months now stocked with plants and peaceful fish. I had about 12 cardinal tetras I had 2 die off in the very beginning kept 10 for atleast 5 months but recently I’ve seen some pass away and I’m curious why? Also they could be prego I’m not sure so if someone can help that would be amazing.

Feed every 2-3 ish days more or less consists of tropical pellets, freeze dried black worms and frozen blood worms.

Tank mates:
10 panda corydoras
4 Ottocinclus
2 clown plecos

Parameters “checked today”
Ammonia 0
PH 7.0-7.6
Nitrite 0
Nitrates 5-10ppm mostly 0 because of plants I’m trying to raise them a bit for red plants

Filter: Aquarian quiet flow 400 canister filter with lily pipes

Anything helps Ty.