Old Pool, New Idea

Greetings,
I have an in-ground, indoor pool that has been sitting empty for about 12 years. It’s a 30’ diameter circular pool with a uniform depth of 12’ (about 65K gal.), shotcrete construction with a plaster finish. The plaster has a lot of fine, hairline cracks with calcium deposits that have seeped through in places. Otherwise, structurally, everything seems in good shape.

A sump pump keeps groundwater from accumulating around the base of the pool (a hydrostatic relief valve was not installed when it was built). The building has stayed at a high enough level of humidity that the walls and base of the pool have stayed fairly damp. It has not been subjected to any freezing conditions. The water circulation fittings and piping seem fine, although a little ground water seeps into one of the two floor drains. The original pump, filter and heater have been junked.

I have serious notions of getting this beast up and running again, but as a freshwater tropical aquarium (!). I’m thinking 76-78 F., a few large fish and a couple schools of small fish, artificial plants, maybe sand on the bottom, etc. Swim with the fish or observe through the 4’ x 5’ observation window that’s already in place. I’m researching options for water filtration and treatment that would be appropriate to keep fish happy and healthy at the aquarium/fish sites.

My main question for this site is: What are my options for sealing/waterproofing the plaster finish in a way that is non-toxic, durable and not prohibitively expensive? I welcome any advice and/or attempts to talk me out of this notion before it becomes a monetary black hole.

Thanks