I don't think I've ever posted in the fish keeping section before, being a cat and dog person, but a stickleback has appeared from nowhere in my little pond. The pond is not much bigger than a child's plastic pool, it's circular, less than 5 ft across and about ten inches deep. It has various plants in it and a couple of frogs.

I don't know what to do about this fish. I'm worried it might upset the frogs, and I wonder what it's getting to eat. Should I just ignore it or do I need to do anything? All advice gratefully received.

hmmmmm this is a tough on XD

if the pond is fairy mature, and has a good lot of plant cover/muck on the bottom, then it will be living on the little invertabrates living in the roots and silt most likely. i highly doubt he will upset the frogs or any other life in there thats bigger than its mouth, so id just let him do his own thing.

as for how it got there, its likely that it was caught by a bird in its native water, then dropped by the bird into your pond. its the only explaination i can think of beyond a human putting it there on purpose. a similar thing happened here in Hull last year, when a group of local school children came outside for lunch, and found a live crab from the seaside scuttling around the playground, 5 miles or so from the nearest salt water!

Thanks for reply. There are quite a few plants in my little pond so that explains how the stickleback is eating. It could have been brought by a bird but I'm in the inner city and we mostly only get wood pigeons drinking in it. I did buy quite a few plants in the summer that were intended for a decorative barrel and I wonder if the fish could have come as an egg in the plants by any chance? It's about two or three inches long so I don't know how old it is, it looks adult (not that I've seen one before!), which might rule out my theory?.

Stickleback eggs are adhesive, so they can quite easily stick to the feathers or legs of water-going birds such as coots or herons. Perch (Perca flavescens) also use a similar method of dispersing their young, as their eggs also posess these adhesive properties. This way, birds can carry the eggs from one body of water to another.

That's interesting. Do you know how long it takes for the egg to turn into a full grown stickleback fish? I still wonder if it's more likely the egg was attached to one of the plants I bought, as I live in a really built-up inner city area and we just don't get any water birds, only wrens, sparrows, bluetits and wood pigeons. Maybe a water bird dropped the egg onto the plants before they reached me? I've not seen the stickleback lately, but I assume it is still there because it probably doesn't have any predators in my little garden.

Were the plants kept outdoors before you purchased them? The stickleback could have come in on the plants.

Stickleback eggs can take upto a month to hatch, during which time the male will defend the next aggressively from predators.

Fortunately, Sticklebacks are a native UK species and they shouldn't be of any concern to the frogs. Normally, most frogs and toads should be quite capable of consuming newly-hatched Sticklebacks, given their diminuitive size.

Fantastic informative post yet again!
We learn something new every day!

I should also say that our own native species of freshwater Perch, the European Perch (Perca fluviatilis), also produces adhesive eggs.

Perca flavescens is the scientific name for the Yellow Perch, a close, if smaller relative. The Yellow Perch is native to North America, including Canada.

I would guess that the plants were kept outdoors, as the address they came from sounded very rural. I noticed a couple of water beetle type creatures that hadn't been in my pond before, too (maybe the stickleback ate them as they're gone now).

So if frogs can eat newly hatched sticklebacks, it sounds like my stickleback maybe appeared fully grown, otherwise the frogs would have eaten it in such a tiny pond as mine? It's quite a mystery.

Could you PM me with the address? I can look it up on Google Earth and take a look for any nearby expanses of water, which would of course attract water birds.