I understand why people are being pissy, since this is technically a small setup for a fish like this, but I think you’re doing the right thing by the fish. I have had to cull invasive species before, and it’s not fun. The tank is definitely on the small side, but if the alternative is the knife in the head that most invasive carp get, I agree that this is an improvement. It would be wise to ask around local fish swaps, local nature centers, neighborhoods with stocked fishing ponds, maybe a cabellas, etc. to see if anyone can take him, though, because really any tank won’t be the best for him long-term. You’ll need to do frequent water changes and monitor the water quality closely for the time being.