Question
My outdoor pond is approx 2.50m x 1.25m.  We have 16 fish and now appear to have 17/18 toads (frogs?)and increasing.  How many toads should I allow? I want to add a few more fish. Regards

Answer
First, you need to figure out if they are frogs or toads.  Then, what species they are and if they are only coming to the pond to spawn and will then leave.  Where do you live?  Frogs have slippery skin while toads have bumpy, drier skin.  If you send a photo of the frogs or toads, I can at least tell you which they are if not the exact species.  I'm mostly familiar with US species but I'm guessing you're in another country since you used meters.

If your pond is say 1 foot deep, then it's 250 gallons maximum.  If it's deeper, then there's more volume.  How big are your fish and what species are they?  If they are goldfish, it will get crowded in there if they are mature.  If they're koi, it's beyond crowded.  If they're minnows, it's fine.  

Anyway, if the frogs or toads are coming just to spawn, they will leave soon.  If they are in fact aquatic frogs who will stick around, and you have too many, if they are wild, you might relocate some to a local natural pond.  I've never had a problem with too many amphibians long term but sometimes you'll get a bunch short term.  Predators often take a lot of them as do things like fungus, death during the winter for those species that overwinter underwater, and so on.

My amphibian pages start at http://www.fishpondinfo.com/frog.htm

Good luck!