[Shadowkiller]

Poisonous = ingested toxin (usually attacks stomach lining or bowels, possibly nervous system)

Venomous = injected toxin (usually a nerve poison). Marine toxin of this type are usually protein based, so hot water can be used to treat the wound.

Ciguatera = marine algae aka dinoflagellates (dont say it Sven!) produce ciguatoxin which accumulates in fish flesh. Its a toxin that goes for the nervous system. Possibly can be absorbed through the skin as well.

Poisonous fish in the tropics usually belong to the Tetraodontidae family. Commonly known as the Pufferfishes.

Venomous fish include the Scorpaenidae family, aka Lionfish, Stonefish and Scorpionfish.

Species which can carry ciguatera include the Balistidae and Monocanthidae families (Triggerfish, Filefish and Leatherjackets), as well as any large predatory fish such as Coral Trout, Barracuda, Spanish mackerel, Red Bass and Chinaman fish. The bigger the fish, the bigger the risk.

Best course of action would be to get a Fish ID book for the area you are diving and fishing, and check out those family of fishes.