stores can be rotten and greedy- which is why this is so not your fault, and why I am so sorry you and your kids are going through this. I think it is wonderful that you are working so hard to take good care of your fish.
does anyone know about the marbled bichir...and also can i have a sandy substrate with an undergravel (i guess the key word here is gravel) filtration system? i'm thinking no but curious none the less
you might pm dolphin 7, she knows a lot about bichirs. I love them but don't have any personal experience.
You'll work through this. It's just going to take a bit of thinking about which fish you really want, you know? nothing wrong with that.