Sockeye salmon for courtship. If they waste too much energy, they might not be able to spawn. Males must also make the decision whether to invest energy in fighting for a female or for longevity on the spawning grounds. Aggressive behavior displayed by dominant males is predominantly directed towards intruding dominant males. Sometimes sockeye salmon males behave aggressively towards subordinate males. These encounters are short, with the intruding male leaving after one or two aggressive interactions. Spawning females direct their aggression primarily towards intruding females or other spawning females that are close by. However, they may also direct aggression towards intruding or
Paradise fish less aggressive than the wild type, but also less hardy, having more trouble with low temperatures. Paradise fish The paradise fish, "'paradise-fish"', paradisefish, or paradise gourami ("Macropodus opercularis") is a species of gourami found in most types of fresh water in East Asia, ranging from the Korean Peninsula to northern Vietnam. This species can reach a standard length of , though most are only about . Paradise gouramis were one of the first ornamental fish available to western aquarium keepers, having been imported 1869 to France by the French aquarium fish importer Pierre Carbonnier in Paris. The paradise fish is