[pvaldes]

They are basically incompatible. Fishes eat frog eggs. Frogs eat small fishes. Ponds without fishes sustain a much higher diversity of invertebrates and amphibians (and this means more clear water).

If the pond is of a decent size and amphibians could hide in the margins, fishes could work. Yes. Native species are much better. In very small ones just toads and newts are a satisfying choice. Add frogs if you don't mind noise.

If you have a place for a mini pond my advice is, don't built it.

Go for a small pond instead. Miniponds look nice on yoputube but are really unstable, and much more difficult to manage long term. They "boil" in a few hours at full sun. Freeze in winter and water must be added all the time. Is the same mistake as starting aquaria with a too small tank. Most people just will quit the hobby in a few weeks.

[skyfaller]

What constitutes a small pond rather than a mini pond in your opinion? Like, what do you think is the minimum size for a stable pond ecosystem? Does depth or surface area matter more?

[pvaldes]

Less than 100 Liters is very difficult to manage but aim for 500-800 Liters at very minimum because you will want to make your pond bigger later. This can fit in any a little boring coin of a garden and will became the best part of the garden. Everything in a range of four to ten liters is not a pond, is a dog bowl and will became a mosquito nursery. I see those often adviced by youtubers that never tried to manage a pond seriously.

Beware. Ponds of all sizes are dangerous for toddlers and ponds must have a side with a gently slope so falling pets and animals can climb out. If you have children of less than five years, you --must-- cover the pond with a solid iron pond cover:

https://duckduckgo.com/?q=pond+cover&t=newext&atb=v411-1&iax...

Apart of this the "deeper" the pond the more animals will fit for the same price. More than 1 meter is normally unnecessary in a small garden