What can I put in my fishtank
August 9, 2018 12:06 AM   Subscribe

I picked up a 28L tank secondhand, planning to put a goldfish in it. Turns out they actually need really big tanks and this is too small. What would be good in an unheated tank of this size?
posted by KateViolet to Pets & Animals (17 answers total) 2 users marked this as a favorite
Maybe shrimp?
posted by Harald74 at 1:43 AM on August 9, 2018 [1 favorite]

The word you're looking for is 'nano tank.' Does your tank have a filter in it? If I were you I'd shell out for a tiny heater (they're not expensive) so I could keep small, colourful, easy care tropical fish like guppies or tetras.

You should be careful to properly cycle your tank before you add ANY critters, though, ESPECIALLY in a small tank. It takes barely anything to disrupt the chemistry in a small volume of water.
posted by nerdfish at 1:52 AM on August 9, 2018 [1 favorite]

Yes, cherry shrimp (Neocaridina) are a good option for a small tank. They're happy at temperatures in the mid-70s (F) and don't get too stressed if the water parameters aren't perfect. Add some natural landscaping - maybe a small piece of bogwood with aquatic moss, and a couple of smaller plants - and they'll have places to hide. They'll eat algae that forms naturally in the tank, topped up with a tiny pinch of crushed fish flakes once in a while. Although normally red, there are yellow, green, black and even blue varieties of cherry shrimp.

If you really want fish, a few guppies will do fine in an unheated tank, as long as your home is a comfortable temperature. Be prepared to do a partial water change every week though.

It's not so much the volume of the tank that's an issue as the fact that it has a small amount of water that (a) gets polluted quickly, and (b) doesn't have the capacity to build up enough beneficial bacteria for bio-filtration. You can solve the problem by using a decent-sized external canister filter with lots of biological filter media, which is basically how aquarium shops can keep large numbers of fish in small tanks. But I'm guessing you don't want to throw a load of money at the problem.

Aquascaping can been fun, but it's time-intensive and probably only for the sort of person who enjoys things like bonsai.
posted by pipeski at 3:17 AM on August 9, 2018 [1 favorite]

Unheated? The perfect fish for this are White Cloud Mountain Minnows.

They are almost supernaturally tough, water temp can go down to 7 degrees c. They don't make a mess. They are peaceful, and they are (in my opinion) a very pretty fish. Also, they're tiny, so you could get a few for a tank that size.
posted by smoke at 3:46 AM on August 9, 2018 [2 favorites]

If you're good with just one fish, you could make a very nice home for a betta fish.
posted by Mchelly at 5:57 AM on August 9, 2018 [1 favorite]

If you're good with just one fish, you could make a very nice home for a betta fish.

A heater would be necessary.
posted by jgirl at 6:56 AM on August 9, 2018 [3 favorites]

If you decide to get guppies, know that you will have MANY guppies in a very short period of time. They are.. prolific.. breeders. As a child, I was delighted when a neighbour offered me some free guppies - several months later, I understood why that neighbour was so delighted to send my new friends home with me. (They are really neat fish, however!)
posted by VioletU at 7:28 AM on August 9, 2018

I've got a tank similar to your size and filled it with plants and have been keeping water snails in there. I think I've got about three different types of snail in there (none of them are the snail eating kind). I've kept them in there for several years now without a heater or filter and have had no problems.
posted by sockpim at 7:54 AM on August 9, 2018 [2 favorites]

The nanotank subreddit is a pretty good place for informative inspiration for a tank that size!
posted by DSime at 8:31 AM on August 9, 2018 [1 favorite]

As smoke writes, White Cloud Mountain Minnows will be perfect. We had some in a similar size unheated tank for years. They're pretty, and undemanding.
posted by anadem at 8:49 AM on August 9, 2018

Is that "28L" meaning 28 liters, or "28 long" which is a pet-store way of saying "28 gallons but longer than it is tall"? 7 gallons is pretty small but 28 gallons is respectable.
posted by The otter lady at 9:36 AM on August 9, 2018 [1 favorite]

28 litres!
posted by KateViolet at 11:11 AM on August 9, 2018

If you find yourself leaning towards fish that need a heater, this is a very suitable one for 7 gallons that I have in my betta's tank.
posted by foxfirefey at 5:04 PM on August 9, 2018

I'm confused why you would need a much larger tank for goldfish. I kept a goldfish alive in a smaller container (a bowl) without a heater or filter for fifteen years. Pedro (his name) was a common feeder-type goldfish--nothing exotic. But still.
posted by Transl3y at 6:48 PM on August 9, 2018

Were you told that your tank was too small by somebody trying to sell you a bigger tank?
posted by w0mbat at 7:32 AM on August 10, 2018

To head off the goldfish questions, goldfish suffer in small tanks and bowls. They produce a LOT of waste, but sadly, are hardy enough that many can just linger for ages in conditions that would kill other fish. Goldfish need big tanks.
posted by fiercecupcake at 8:00 AM on August 10, 2018 [5 favorites]

Coming in to second what Fiercecupcake said. Goldfish are like little cows - if you watch them they're forever sucking algae off gravel, basically grazing - and they poop CONSTANTLY, also like little cows. All this poop dumps a lot of ammonia into the water, and in a small volume of water this can quickly throw off the pH balance. A lot of goldfish die pretty quickly in poor water environments like this; some don't, but it's far from humane to keep them in small spaces. Goldfish do better in large tanks with good, strong filtration and regular cleaning/water changes. Just because you can keep an animal in a tiny tank doesn't mean you should.
posted by nerdfish at 5:00 AM on August 12, 2018

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