View Full Version : Aside from minnows and danios ....

10-11-2010, 04:41 AM
What other species of coldwater FW fish stay small enough to thrive in a 20-gallon tank? What invertebrates besides snails would do well in one that size? Minnows and danios are fine, but I like variety.

By the way, my goldfish are back in their pond .....

-- mermaidwannabe

10-11-2010, 06:17 AM
I can't really think of any. What is in the tank now?

10-11-2010, 02:38 PM
Seven White Cloud minnows, two Hi-Fin bottom feeders, a Dojo and some snails. That's it, for now.

10-11-2010, 02:49 PM
what temperature range do you expect it to be at? There are a lot of fish that aren't usually called "coldwater" but will do fine at average room temperatures.

10-11-2010, 04:13 PM
I expect the water temperature to be anywhere from about 55F up to about 62F with the average about 60F. During winter my fishroom will be colder, however, I have a space heater located several yards from the tank that will warm the room up a bit when I'm in there. There is some vented heating we had installed when the house was built, but because the contractor did it wrong, it's rather ineffective. Hence the need for the EdenPure.

I know the minnows like it cold, and right now the water is cool enough that their colors are shining through brilliantly.

I don't think the Dojo cares much, as long as it doesn't get too warm, and the Hi-Fins are active and feeding, so they're at the temp they like.

I should probably invest in an aquarium thermometer, but never thought I would need one for non-tropical fish. There's no heater in the tank.


10-11-2010, 04:34 PM
okay, that's coldwater for sure. yeah, your options will be pretty limited at that temperature range.

10-11-2010, 05:14 PM
If it gets up to around 65 to 68F, would the other inhabitants still be comfortable, and maybe allow for a few more stocking options, as long as they stay small enough to not overcrowd the tank? What would be the better temperature range for the type of creatures you're thinking of?

Aquarium heaters are mostly gauged for tropical fish, aren't they? There's no good way to set one so it keeps the temps within the lower ranges -- say 65-68? I wouldn't want my coldwater tank to get into the 70s.

Also, what species of danios can take colder water? Zebras come to mind, but when I had my earlier tanks, they were considered tropical fish and I put them in with tetras, in a warmer tank. I recall the Zebras were always sold as tropicals. If they can withstand cold water, they certainly are an attractive little fish which I would be willing to consider -- but only if they will thrive in my current set-up.

-- mermaidwannabe

10-11-2010, 05:19 PM
How big are those chinese hi-finned sharks? Those guys can hit 36", I'd say you're overstocked with them in there period.

10-14-2010, 03:07 AM
Right now, they're only two inches long, and I read that they grow very slowly. I know they will eventually get very large. By that time, I will either have a system large enough to accommodate them, or I will rehome them through sale or donation. At the moment, they are very fun to watch, and their black and silvery banding is striking to look at. I got two of them because I also read that individuals prefer companionship of their own kind. They seem to be excellent ground feeders.

When I get my 60 or 70-gallon coldwater tank, I will relocate them to that larger tank, into which I shall also house my goldfish. This should give them more room to grow somewhat larger, though of course, it won't accomodate their full adult size. By then, I will have made other arrangements.

I'll probably donate them, eventually, to a public aquarium that has very large tanks.

-- mermaidwannabe

10-24-2010, 04:00 PM
I came across this info at a website on cold water fish.

"3. More Good Fish for a Cool Water Aquarium
Fancy Goldfish are available in many interesting shapes and beautiful colors. White Clouds, Crabs, Ghost Shrimp, Tadpoles, Aquatic Snails, and Live Plants all do well in a Cool Water Aquarium with Goldfish, and all can eat the same food such as TetraFin Flakes.

If you are looking to add a bizarre fish, a Dragon Fish may be just perfect for your aquarium. But keeping a Dragon Fish requires more skill than keeping Goldfish, and Dragon Fish need to eat live food such as Ghost Shrimp. Click here for more information about Dragon Fish."

This is the website I found it on.

10-24-2010, 10:11 PM
Whew -- thanks much! That's good to know.

-- mermaid

Michael Milligan
10-25-2010, 10:29 AM
What other species of coldwater FW fish stay small enough to thrive in a 20-gallon tank? What invertebrates besides snails would do well in one that size? Minnows and danios are fine, but I like variety.

By the way, my goldfish are back in their pond .....

-- mermaidwannabe

Jumping back for a second... What do you mean by 'variety'? In a 20 gal you can grow snakes and turtles and salamanders and spiders and beetles... you get the idea.

Where are you? What do you have there? They don't need a heater? ;) My latest thing is native tanks. Catching my own livestock.

10-25-2010, 11:15 AM
This is an aquarium, not a terrarium. Snakes, beetles, salamanders, etc., unless they are strictly aquatic, that is, living all their lives in water, wouldn't survive in an aquarium where there is NO dry area for them to go to. Ditto for turtles. Whatever I keep in my 20-gallon-high, it has to be strictly a water creature who must live in water in order to breathe. Amphibians and reptiles need to come up for air and have places they can bask outside of the water.

I currently have minnows, danios, a Dojo, 2 tiny Hi-fin sharks, and snails.

I live in the inland northwest, U.S.A.

Any water beetles I would keep can't be predatory. Minnows and danios are quite small, and some water beetles get huge. Conversely, the bottom feeders could eat the beetles.

It's a coldwater tank -- they don't need a heater.

-- mermaidwannabe

10-25-2010, 08:17 PM
The dojo and the danios would do just fine in warmer waters, can't speak for the snail as I don't know what kind you have. Trapdoor snails (not apple snails, the names often get confused) are good in cold water, the others(mystery snails, apple snails, etc)...not so much. Very short lifespans. Same goes for trapdoor snails kept in a warm water tank.
Easiest way to tell is in the mouth.
Trapdoor snails(cold water)-

Apple snails(warm water)-

Of course I am sure there are exceptions, but this is not a bad rule to go by.

Crabs and crayfish will take chunks out of your fish at night or whenever they get a chance.

"dragon fish" are dragon gobies, brackish/rock hard water fish, and they also get quite large. Not going to work in a 20G. And they are tropical IIRC.

I think the suggestion was that you could add some land to the tank, thus enabling more variety. If you are just looking for people to list fish for you, here is a pretty good resource I use on occasion-

Local/native fish are a really good option for coldwater tanks.

10-25-2010, 09:17 PM
Thank you. I think I have trapdoor snails. They are very dark in coloration, their mouths look like the top pic, and they've been alive for about six months, first in my pond, then in my tank. Two of them are in the indoor bins housing my goldfish.

I'm thinking of getting a ghost shrimp. Right now, I'm trying to research its compatibility with my Dojo, and vice-versa.

I was thinking about freshwater crabs, but like you say, they might injure my tiny fish, who do like to feed on the bottom, sometimes.

What about freshwater clams? Those ought to be cool, if they'll thrive in coldwater. I'll be researching them, too.

Thanks for the heads-up about the Dragonfish. If it lives in brackish water, it won't be suitable for my tank, as I don't use salt in it.

And thanks both of you for the links.

-- mermaidwannabe

10-25-2010, 11:39 PM
shrimp make excellent loach snacks.

Clams would work, but they require special feeding and you will only see the very tip of them if that sticking out of the gravel. I keep em in my pond and bring them in for the winter, as they can take cold water, just not borderline freezing water. you would feed them the same thing you feed SW clams.

10-26-2010, 12:19 AM
What would one feed clams? I'm thinking I would have to use a syringe to make sure the food actually got into the clam's "mouth".

-- Mermaid

10-26-2010, 04:20 PM
Look into the foods used for saltwater clams.