I want to start a "snail farm" for a goldfish friend

[KittenFishMom]

I have started setting aside some of my bladder and ram's horn snails in a bucket with substrate on the bottom and an air stone and a chunk of driftwood for the friend that took my goldfish. I feed  them a pick of fish food now and then and algae wafers and plant trimmings. They are doing well, laying lots of eggs. I wanted to set up a small aquarium for them so she can hove them on a dresser, where her dogs won't tip them over.  What would be a good minimum size tank for the snails?  Do you think the snails would benefit from some fish in the water? 

The plan would be that she could feed the goldfish live food now and them to supplement their dry food. This would be an ongoing source of food. 

Any thoughts?

[Flumpweesel]

I'd pick something that could sit on a window sill therefore generate the algae the snail want to go nuts. 

Look at some of the "scapes from scraps" projects for inspiration 

[TOtrees]

It's a rabbit hole. 🙂

I bred ramshorn snails, first for sale/trade directly, then when that market dried up I transitioned to assassin snails (still breeding ramshorns for their food), and I even kept a few dwarf puffers for a way to have something to do with extra snails.

I found that it's very hard to maintain the line between "they're doing ok" and "holy heck slow down!". You want to feed heavily to make more snails, and boy do they oblige. You end up with boatloads of tiny snails, too small to do anything with, so you keep them and feed them till they are bigger. But in that time they continue to breed, and population explodes. 

I found that they inevitably stripped the calcium out of the water, even with adding it back in via Dr Turtle (like wonder shells), crushed coral substrate (lots of it), and even direct addition of baking soda. With no calcium, kH was very low and pH crashed. Not the end of the world for their biology because ammonia isn't much of an issue at low pH, but low pH and low kH don't result in good snail growth/health. I tried adding generous amounts of equilibrium, but that drove up gH only not kH. Any calcium that was added in any form the snails could use, got consumed immediately. Their shells were heavily pitted, and even though I was making a ton of snails, they were not at all sell-able. 

You might plan on restarting the setup every few months, but if you're growing enough snails to feed them to the fish, you'll probably have the above problems and more. If you have that many (small) snails on the go, then a reset will involve some amount of... reducing the population. Maybe a huge feed for the fish, just keeping a few snails aside for the next generation, or humanely euthanizing - which IMO defeats the purpose of breeding/raising them. 

I'm not saying don't do it, but I am saying be cautious, and aim low not high. 

[KittenFishMom]

@TOtrees Thanks for all the useful info.  Around here driveways and roads that are not paved are topped with crushed lime stone. I wonder if a low Ph would free up calcium for snails?  Maybe tossing in some cooked and cleaned soup bones would do the trick. They are softer when cooked.

Note: This would be to feed 3 smaller goldfish in a 20 gallon tank.  This isn't on the scale to sell or anything. 

[TOtrees]

My snail farm was in a 10 gallon. I don't think crushed limestone or bones would provide more available calcium that the methods I used. But I didn't try them, so that's my opinion not facts. Also, due to the assassins, the bottom of the tank was littered with snail shells in various stages of disintegration. So it's not that there was no calcium sources in the tank, it's more that any available calcium was immediately used/converted. 

As an aside, personally I would never consider putting something from the road into a tank. Fumes and gasses and petroleums and metals are all things that won't show up in testing, and will remain invisible to the naked eye. 

Try it and see. For the first few months, at the scale you're implying, I don't see you'll have any issues. 

[KittenFishMom]

Oh we have piles of crushed lime stone that was never on the road or driveway to fill pot holes. I would use stuff that had been driven over. 

A lot of stones in the local creeks/streams have one side that is white from calcium. Those might give up the calcium. There is a big limestone deposit here. Most wells have very hard water.

When ever I make soup. I use an acid, like wine or tomatoes or even vinegar to help get the calcium out of the bones and into the broth. I could scrub (no soap) those bones and put them in the sun, away from raccoons and such to get them ready for the tank.

The mice such in the north eat antlers for calcium. That is why it is so had to find dropped antlers in the spring.