ponds and pine trees

I am getting ready to dig in some 300 gallon Rubbermaid tubs for fish outside. Do I need to stay away from fine trees so that needles don't fall in the tubs ? I have heard that pine needles can give off toxic stuff that would be harmfull to fish.

I've read some websites that caution the use of pines around fish (koi) ponds, due to the potential toxicity of the needles. The conifers are a very diverse group of plants, so it is likely that some are more toxic than others. Pine needles (straw) are an important link in blackwater ecosystems in the southeast. They reduce pH and increase dissolved tannins, which changes the food chain by reducing suspended algae production. If your goal is to maintain "swamp" fishes (Enneacanthus, Elassoma, Amia, Pteronotropis, etc.), I would intentionally put the ponds near pine trees. You will need to remove needles occasionally as they build up on the sediment. My 165 gallon pond is located beneath a small Japanese Black Pine, which of course is not native, but I've had no problems. Knock on wood...