I added 4 to my pond in June. Between June and August the mosquito fish
(MF) population exploded. I would estimate it to be over 500--probably
more like 1000 in my 1350 gallon pond. For the past couple months I
believe the MF has pretty much balanced as far as I can tell. I have 6
koi (only 1 old enough to spawn), 2 dumb goldfish(rescued/donated to
pond - born pregnant) and 2 comets (old enough to breed). Well, the
mosquito fish try to eat anything... and are pretty successful with
things under 1/4 of an inch. This includes fish eggs and baby fish. As
a matter of fact, when the mother mosquito fish are giving live birth
they are followed around by other hungry fish awaiting a new meal/birth.

My pond is lined with rock (10 - 40 lbs each) and has alot of plants so
there are lots of hiding places for baby fish. This helped my mosquito
fish population grow. As for other pond fish, I have maybe 10 pond
mutts that have survived the egg stage and hid long enough to not get
eaten while small. From what I can tell, the ones I see are from at
least two different breeding sessions given there sizes.

If I had it to do over, I would. Yeah, there are a lot of fish... but
they are fun to watch swarm around the pond and you see fish every where.

Chad