Sometimes I just need one single sized aquarium, not a whole set. Can you sell them in singles? Crafting is not an option as the ones I need most are just the regular aquariums and treantfishes are impossible to catch. I have found some epic fish that were easier to catch. I think you would sell tons more if we could buy what we needed.
In our update today, the crafting recipe for the regular keeper aquarium has changed to no longer require a Treantfish. It instead uses a Lifeacuda. I hope this helps you craft the regular aquarium easier!