I have pygmy cories in a 12 gallon edge. I lost a few over a matter of days. They were added to the tank about 2 weeks ago.
I think I lost the first one because of ammonia. The tank was cycled but I think the number of fish added created a small amount of ammonia (looks like a little less than 0.25). I've been doing daily water changes since then and there has been zero ammonia for 3 days now (it has been zero since the first water change I did after I discovered ammonia). The latest test results are shown below.
I'm also concerned that they may not be getting food. I've been trying all kinds of food. Daphnia, ground freeze dried brine shrimp, micro pellets, grated blood worms and algae pellets. I still haven't seen then eat properly. I feel terrible for them and I want to make sure I don't lose anymore so any advice would be appreciated. Thank you!
Other inhabitants: 3 danio erythromicron which seem to be doing just fine (got them at the same time)
I give mine shrimp sticks that fall to the substrate and earthworm sticks. They are for bottom dwellers such as cory's and mine love them,. I've never seen any Cory I've ever had eat algae wafers that I drop for others pleco's that I have, or go near zuchinni or cucumber. If you go into a petco and look at the food you'll see little bags with pictures of Cory's on them, they will sink and they will eat. Good luck with you fish