I had great success last year and am doing it again this year on a much larger scale, Things to watch out for, if its ground level animals and birds can get in and out with out any issue, if its above ground its hard for birds to land in it and animals to hold them self on just a little edge.
Be mind full to direct sun light as the hot summer days will cook the water if it has lots of direct sun light.
I didn't see any parasites in the water as cichlids are known to eat nearly every parasite they can possible find in the wild lake sands and shallows.
I really only worry about large crane that can wade in the water and graze as they may like and water temp.
I'm not really willing to set up heaters in the ponds so I'm just risking it but do wait for the temp to be consistently over 70 during the day. I think people are much to cautious when it comes to the temp as they can handle short term temps in 60 degree water and if you have 300 gallons it takes a long time for it to cool down but easy to warm up with minimal direct sun light on that black plastic. I try to place mine where they will get a few 2-3 hours of noon sun light and then back into the shade. Last year I didn't put any plants in it but this year I will have them covering the top to help hide them from predators.
It is a huge pain in the buns to wade in the water in the fall and try to get all the fish out I kept them out in the fall till the first frost and I should have took a water temp at that point in time cause the water made my hands and feet go numb but all the fish made it except for 2 which were found floating like 3 weeks later when it really got cold not to mention 90% of the water was out so water temp dropped alot faster on the forgotten few.
