Tell me if this experiment will work: above-ground fish pond

I’m building a pond on my back porch, made of white limestone blocks masonry joints. The dimensions are approximately 6x4. The porch itself is cement.

Originally I was going to put in one of those ugly black liners, but I now I’m thinking I’ll seal the inside joints with fish-safe clear silicon instead.

Will this project work, or will the whole thing wind up leaking like a sieve?

I’m thinking a three foot high wall, with about two feet of water.

Thanks!

I believe limestone is somewhat porous and I know that mortar is. How about clear plastic maybe 10 mils in thickness?

One issue will be the pH of the pond, which limestone will raise (i.e. it will become more alkaline). Limestone is often used in fish ponds to prevent the pH from becoming too low. Koi seem to prefer slightly alkaline water, but you’ll probably want to keep an eye on it and adjust if necessary (which a pond owner should really do anyway).

What they said. Limestone is not impermeable and is not inert chemically. Fish are easy to poison, and tanks are hard to keep sealed with the best of materials. I think you are going to be very disappointed and your fish will be dead.

Just my tiny opinion.

and limestone does dissolves in water…

Also…unless you live in a very temperate climate, won’t two feet of above-ground water be susceptible to fairly extreme temperature swings? I don’t think that’s good for fish either.