unheated greenhouse fish ideas

[Sgooosh]

Hi, I will be having two 27gallon large tubs, or maybe an even bigger one 40+gallons in my greenhouse for temperature regulation, and I’d like to keep a few larger fish in there (as in larger than a swordtail, not monster fish).

I'm in a very bipolar part of zone 9b, and the coldest it gets outside is just freezing for an hour or two in the middle of the night. Water never freezes even in my outdoor seasonal tubs, which tropical plants (Giant val) are able to grow in.
With the thermal masses including the water and pots/composting stuff going on, I plan for the temperature to be around room temperature.
Another note is that my pearl gouramis in my house, when i forgot to add a heater in the winter, slow down quite a lot. my other fish seem to fare alright with room-temperature tanks.

Wondering if you guys have any suggestions?

 

[Colin_T]

A 40 gallon container isn't that big and the temperature in the water could vary a bit throughout the day and night. Insulating the outside of the container with 4 inch polystyrene or polyurethane foam rubber would reduce the fluctuations. A bigger container would also fluctuate less.

We put bubblewrap on the surface of the ponds over winter. We cover about 90% of the surface and it helps trap heat in the water. If the sun shines on the bubblewrap, it warms the water. The bubblewrap floats due to the air bubbles in it.

You can get 1 meter cube aquaculture ponds that hold 250 gallons and will have a more stable temperature.

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Giant Vallis is a coldwater plant and lives in water down to just above freezing up to 26-30C. It normally does better in cool water than hot water.

Your pearl gouramis (and all gouramis and Bettas) are tropical and it would take a few years of breeding them outdoors to get a cool water strain.

Barbs, livebearers and rainbowfish will all be ok outdoors to a degree. If it gets down to 10C you will probably start losing them but if you breed them outdoors you might get some survive and those will be the start of a cold water strain.

 

[GaryE]

Zone 9b. I would take a good look at your native fish. There are some really nice ones in that zone. Poecilia latipinna sailfin mollies, two or three killie species, some nice minnows and sunfish.

You might be surprised at how nice unhybridized American mollies can be.

As long as you never get a film of ice, Macropodus opercularis, the paradise fish would be ideal. Large, colourful, smart and producers of cool bubblenests in summer. They can handle close to freezing (as long as they can get to the air they breathe at the surface) all the way to scorching heat.

 

[Magnum Man]

I certainly understand, if you’re wanting to run them with no heaters… but adding one, can stabilize your water temperature better, and it’s surprisingly good as a radiant heater for your greenhouse… I have an unheated, but insulated entryway into the house, the in the deepest winter, pop cans would freeze, I set up a 65 gallon, and a 45 gallon aquarium in there to hold over my Tilapia to breed over winter, and my normal aquarium heaters keep the tanks hot enough, even in the coldest of winter, to get the fish to breed, as a by product, the entryway stays a comfortable temperature all winter… so in your more temperate climate, it wouldn’t take as much electricity, and may make for more vigorous plant growth over your cool season…

 

[Back in the fold]

Isn’t there also a loach that does well in cold water ? The Weather Loach ?

 

[Sgooosh]

A 40 gallon container isn't that big and the temperature in the water could vary a bit throughout the day and night. Insulating the outside of the container with 4 inch polystyrene or polyurethane foam rubber would reduce the fluctuations. A bigger container would also fluctuate less.

We put bubblewrap on the surface of the ponds over winter. We cover about 90% of the surface and it helps trap heat in the water. If the sun shines on the bubblewrap, it warms the water. The bubblewrap floats due to the air bubbles in it.

You can get 1 meter cube aquaculture ponds that hold 250 gallons and will have a more stable temperature.

-------------------

Giant Vallis is a coldwater plant and lives in water down to just above freezing up to 26-30C. It normally does better in cool water than hot water.

Your pearl gouramis (and all gouramis and Bettas) are tropical and it would take a few years of breeding them outdoors to get a cool water strain.

Barbs, livebearers and rainbowfish will all be ok outdoors to a degree. If it gets down to 10C you will probably start losing them but if you breed them outdoors you might get some survive and those will be the start of a cold water strain.

okay, I have giant pads of fine filter foam and also packing insulation that would be good for this.
I will think about those! I can test my strain of outodor wild guppies with the tank, and if they start to slow down I'll just bring them back.

Zone 9b. I would take a good look at your native fish. There are some really nice ones in that zone. Poecilia latipinna sailfin mollies, two or three killie species, some nice minnows and sunfish.

You might be surprised at how nice unhybridized American mollies can be.

As long as you never get a film of ice, Macropodus opercularis, the paradise fish would be ideal. Large, colourful, smart and producers of cool bubblenests in summer. They can handle close to freezing (as long as they can get to the air they breathe at the surface) all the way to scorching heat.

the sailfin mollies are not native to CA or not introduced to this part at least, but I think they are beautiful and definitely a good candidate! I will also search for the killifish that live in lower temperature, I haven't found any so far in local stores. I will definitely get a paradisefish! Do you know if they are suitable to be kept with other paradise fish or other types of fish?

I certainly understand, if you’re wanting to run them with no heaters… but adding one, can stabilize your water temperature better, and it’s surprisingly good as a radiant heater for your greenhouse… I have an unheated, but insulated entryway into the house, the in the deepest winter, pop cans would freeze, I set up a 65 gallon, and a 45 gallon aquarium in there to hold over my Tilapia to breed over winter, and my normal aquarium heaters keep the tanks hot enough, even in the coldest of winter, to get the fish to breed, as a by product, the entryway stays a comfortable temperature all winter… so in your more temperate climate, it wouldn’t take as much electricity, and may make for more vigorous plant growth over your cool season…

yes! I do plan to add a power cord into the greenhouse at some point for fans and whatnot, but I'd like to start cycling the tanks( and have no mosquitoes) in the new greenhouse.

Isn’t there also a loach that does well in cold water ? The Weather Loach ?

those are pretty cool! However, i see that they require a large tank, and I'm not sure if i'll be able to handle like a massive tub in the greenhouse. Do you know if they'll be okay in 27 gallons?

I also see those cheap rosyred minnows in fish stores, wondering if those are able to be kept and bred in room temperature?

 

[GaryE]

I wasn't sure where in zone 9b you were. California is way west of the cool fish.

I put a couple of paradise fish in a school pond, and took out hundreds when the water got cold. They did fine in a 75 gallon in a large group.

There's a US seller, Jonah's Aquarium, that carries native fish, although not native to your region.

 

[Archerfish]

All good ideas above. You mentioned putting fans in the greenhouse. Very important as you know. Have you thought about using a dehumidifier to control humidity? Dehumidifiers circulate air and produce heat.