Dealing with an infestation of ants around a fish pond-what can I do?

If you can locate their anthill, that would be your best bet of solving your problem. You can kill ants by pouring club soda down the hole (carefully, so as not to alarm them you are there before they have a chance to escape).

Diatomaceous earth food grade only!!!

Pour boiling water on them

Have you tried hot pepper juice? It keeps them away for me.

Get some of those new ant traps that kill the colony (not thalamine) that the ant eats, returns to colony and it kills the whole colony. They are clear plastic not the cans or black traps.

About five years ago I built a small patio around my greenhouse entrance. The pavers were laid in sand, and within one day the ants had taken over. I used my old standby "potion" of roughly one part sugar, one part dried yeast, and one part Borax. Sprinkle it around. It takes a couple of days because the ants eat the borax and die, then the others carry the dead ones back to the nest to be eaten. WIth just a few days the problem is solved. I hose the white powder away but use no more water than is necessary so the white powder doesn't show but at least some of the ingredients remain. We have a lot of rain in western Oregon during the winter, so I have to do this every spring around the perimiter of the greenhouse - inside and out - and never see an ant. And, best of all, I don't have to worry about my dog eating poison since he likes to bury his bones in the greenhouse.

I've heard using coffee grounds keeps them away...