I asked this in the PNW regional thread, but at @JohannsGarden’s suggestion I’m pulling it out to be a separate thread:
I’m most interested in species native to the PNW, but I’m also curious about other options that can survive cold conditions, for a zone 8-ish pond (never freezes solid but occasionally a bit of surface ice).
I’ve been curious about this for years and look into it from time to time. One of the biggest issues is that smaller bodies of water like this don’t stay cool enough to keep oxygen levels high enough for many native fish species. I do wonder if they would stay well enough oxygenated if placed where they will not get direct sunlight during most of the warmer hours of the day…
I’ve done very well with non-native goldfish in 200+ gallon stock tanks. I would love to switch to a native option, but for years the goldfish have been great because they survive the water being very warm in summer (located in full sun) and fully freezing over in winter, plus they’ve required zero supplemental feed. The only repeat issue I’ve had is that invasive bullfrogs sometimes show up and eat them, but I catch and dispatch the bullfrogs once I notice them.
I have a powerful pond pump that runs for a few hours every day, it sprays directly into the pond surface, and seems to do an excellent job aerating it. I was also thinking I could add an airstone to help, I have a bucket of old aquarium supplies waiting for their chance to shine.
That should definitely help for native species. It looks like largemouth bass are native and like warm water so I wonder if keeping one or two in your setup could be an option. They wouldn’t reach full size, but that shouldn’t matter much. It looks like there might be people who’ve succeeded at keeping them in fish tanks…
https://www.bassresource.com/bass-fishing-forums/topic/126798-keeping-a-largemouth-as-a-pet/
If you have enough surface plants, either water lilies or things like water lettuce that float, you can keep the water shaded and cool enough for fish.
I use and recommend what are commonly sold in pet stores as rosy reds. These are actually just a color morph of the native fat head minnow, so you will often see tan/silver ones mixed in which are the regular color. They are native to the southeast I think, so not necessarily to your area. They are sold as feeders for larger fish, so are very cheap. The downside is that there are so many in the tanks and they don’t get the best care in most stores, so they often are stressed or sick when you get them. I usually start with twice the number I’d like to have in the pond or tub just to make sure I have some “spares”. They’ll reproduce and keep going for years.
The advantage of the rosy reds vs. the native colored minnows is they are easier to see so you can usually tell there are still some there doing their job. The natural color ones can be very hard to spot unless you’ve got super clear water.
Looks like the rosy red minnows can handle the water surface freezing over. That’s a pro. So is the fact that they’re easy to source. Only con is they’re not native here, but neither is my current option (goldfish).
Here’s a list of species already living here (mixture of native and introduced), and based on that I’m thinking maybe the western mosquitofish is the way to go, if it’s already been introduced and is unlikely to escape from my pond in any case:
Here’s the range map for the western mosquitofish:
Only the orange bit is the native range, the rest is where it’s been introduced (along with most of the rest of the world).
I thought our local winters got too cold for Gambusia affinis.
That map shows them in Montana, we can’t be colder than them, right?? But it is interesting they aren’t shown above the Columbia River in western WA.
I had least killifish (heterandria formosa) for about 15 years in tanks… i fed them the little squiggly things in stagnant water… like mosquito larvae.
Amazing fish to watch as they also have live young. Voracious feeders… especially the larger squigglies… they attack them.
Put in a handful of stringy moss and they will multiply like crazy… then cull after they multiply and put in your pond.
Banded killifishes are voracious eaters of mosquito larva here. my cousin had a old farm pond near his house and couldnt go out in the yard in June without getting eaten. i caught a bunch of killfish from another pond with a minnow trap and we dumped about 50 in there. by the 2nd summer he barely saw mosquitos in his yard and the pond was full of killfish. they are prolific breeders when they have a good food source. get yourself a minnow trap and put some Cheetos in there and put in a pond that you know they exist in. they like being along a weed line. check every 6 hrs or so.
You can try Poecilia latipinna {Sailfin Molly}. They are interesting. Are not bothered by lack oxygen or salt content very much. Hardy enough to be established in North Carolina and Banak’s Lake, Canada. My experience is they do well with other species except in spawning time. They will eat algae most of the time unless insects present themselves. Being larger then Killifish they have quite an appetite for bugs. I just would not release them into the wild.
I used to keep those in a brackish mangrove riparium! I do not think they are generally very good at mosquito control, these quotes are from the species profile:
The Sailfin Molly has been stocked for mosquito control, even though it is largely or completely herbivorous (Courtenay and Meffe 1989).
A failure in Hawaii at mosquito control, this fish has on occasion been used as a tuna baitfish in that state (Randall 1987).
It’s interesting that it’s not been observed in the PNW even though some of the spots on the map seem colder than here:
Here’s an interesting one:
Novumbra hubbsi (Olympic mudminnow)
Native Range: Coastal lowlands of Olympic Peninsula, Washington
Ecology: Generally found in lowlands in slow moving streams, marshes, ponds, wetlands, and other habitats with low water flow, muddy bottoms, and abundant aquatic vegetation. Primarily consumes benthic and aquatic invertebrates (ostracods, isopods, oligochaetes, mysids, mollusks, and insect larvae) (Mongillo and Hallock 1999).
looks good, slow moving soft bottomed waters and eats insects…Now hopefully you can find a source or they are easy to catch!
They are a nice looking fish. Makes me want to make a bigger pond and give them some space to breed and stuff.
Do not know what to say. They eagerly took mosquito’s anytime I found them in the yard and gave them to them. But yes; they like picking algae of things.
I just read the wikipedia on it and it sounds perfect (even mentioning that it handles low oxygen waters). Now to find a source…
Well this includes exact GPS coordinates of places where they were caught by local scientists mapping their habitat:
Olympic mudminnow (Novumbra hubbsi) (4.7 MB)
