Agua Caliente Park in Tucson has a perennial, warm spring and several large ponds filled with non-native cichlids.

There appears to be several different kinds of cichlids there, and I once saw a bright blue one swimming around. These fish are normally found in tropical regions, such as Africa or South America, but Agua Caliente's warm spring waters allow these exotic fish to survive the non-tropical Tucson winters.

In May, these cichlids are busily excavating their nests, large depressions in the sand in areas of shallow water. The nests are crowded together, so the males have to vigilantly guard their nests and this results in frequent, aggressive posturing between the males.

The large fish in the photograph below was having quite a bit of trouble with one of his neighbors whose nest was too close to his. His obnoxious neighbor was busily working on his own nest and spitting the excavated sand into this fish's nest. This poor fish kept making what I assume were nasty faces at the offending neighbor and charging at him when he approached the wall of sand separating their nests.