Backyard Aquaponics
A place to discuss aquaponics

Google is so far of no help in answering this question, and I'm probably just going to have to experiment to find out, but if anyone already knows please throw me a clue.

My mother-in-law is one of those "throw it away if it's past its 'good by' date" and will not listen to reason on the subject. Therefore, today I find myself suddenly in possession of several unopened packages of tofu which "expired" a few days ago, despite being constantly refrigerated.

I'd love to feed the stuff to the fish, but wanted to check if anyone knew if they'd eat it, or if there are any hazards in doing so.

Please let me know, and thanks!

If it doesn't have any visible mould, and isn't slimy, then it is perfectly ok to eat. If it has been kept at the right temperature, it lasts way longer than the expiry date.
I have no idea if tilapia will want to eat it, but it should be fine for them to eat it if it's in ok condition for people to eat.

Most fish will eat anything that is the right size to fit in their mouths.

That being said, there are commercial fish foods that have a large percentage of soy-protein as an ingredient. It's possible that changes to the soy during the coagulation process when making tofu could alter its nutritional profile, but I think it would be safe to feed to fish in moderation. It might be better used as an ingredient in home made fish feed providing more balanced nutrition.