It's a very hard question actually. Look at this sketch:
The bottom one is another pond. It gets water from rain and probably from ground too. Unnecessary water flows to another smaller pond. It's connected to the largest one. So - 2 ponds, rain, snow... who can calculate something?
I haven't even tried to go fishing. They aren't ready for it. Mostly they are little ones but I don't want to harm the larger ones because I hope they would breed this spring/summer(larger tenches).
If not this year then next year it will happen.
