I have a small man made pond in my backyard where the fish numbers= (greater fish effluent in the water) and was becoming to concentrated for the small numbers of tomatoes and lettuces I was growing- (3 tomato plants 100 plus lettuces) which helped to remove nitrates.  The pond water, should be replaced by at least 1/3 every week or two in any circumstance, to keep ammonia levels down. So this year, starting in the spring, I decided to kill two birds with one stone and put in a drip-line system and now pump pond water directly from the pond to my fruit tree's instead of using spigot water.  The results have been truly amazing! My other fruit tree's (Plum, Apricot, Peach,) are putting on tons of growth including trunk size, compared to before, and my figs have 'gone gaga' and are putting on lots of growth and corresponding fruit as compared to city water-(Though our long summer may have contributed as well, I'm sticking to the fish water theory.) I don't think you can over-fertilize, using this method either. So if you have a pond with koi or gold fish I say water with it to grow more vigorous fish and tree's. The only issues are keeping the drip ends from getting clogged with algae, but it only takes a few minutes every so often to clear the drip ends- not a big deal. If anyone else has experiences with this please share as I would like to hear your results. Noel- Banning, CA