I agree Sunil. And I don't know either. In the pond I did reference in CO, the swirls were bigger and the muddoggies were not minor in length. At least six inches long but the water was murky and it took a while before I got a good enough glimpse to identify. It was constant activity but not as dense as that. The activity is more reminiscent of tadpoles to me.
If not tadpoles which BDBeaux notes as abundant, we have to hold out that the creatures are unknown and I think I would like to know the culprit of that activity if at all possible. Sunil, quick question. If they are fish does this change anything in terms of stocking recs?
BDBeaux, quick question. Would it be difficult to find out what kind of fish, if any, the neighbor has?