The trade in ornamental fish is large and global, with much of the trade volume being produced in captivity, representing an important aquaculture industry. Because ornamental fish often originate from tropical climates, aquaculture production is in warm regions such as Florida, where hundreds of species and varieties are reared. The introduction of ornamental fish, whether through aquarium release or escape from aquaculture, affects industry development and sustainability, and is one of the chief environmental concerns for ornamental aquaculture. Our broad goal is to examine the invasiveness of ornamental fish. Our specific objectives were to 1) evaluate the aquaculture escape pathway for the introduction of ornamental fish, 2) identify risk of ornamental fish to the conterminous U.S., and 3) evaluate the causes of successful and failed invasions. We used risk screening of popular species, thermal suitability, and known invasion history to examine invasiveness.
The aquarium release pathway was often found to be conflated with ornamental aquaculture, although they are separate introduction pathways. The ornamental aquaculture pathway was only important for regions with a combination of suitable habitat (warmer water temperature) and significant ornamental aquaculture production (Florida). Ornamental fish are predominantly low risk (non-invasive), with a few exceptions. Even for established non-natives, impacts are rarely known or found. Successful invasions were due to unique microhabitats (hot springs), availability of subtropical and tropical climates, or tolerance to cold temperatures. The causes of failed ornamental fish invasions are often difficult to identify. However, the lack of cold tolerance was a dominant and often obvious cause of failed invasions, likely due to the relative paucity of temperate ornamental fishes, although there has been some development of native North American ornamental species. In other cases, careful experimentation was required, as with the case of the Guppy (Poecilia reticulata), which failed to establish due to native species biotic resistance.