Our first dive after a long, dry spell, and on one of my favorite spots. Down, down into the cool blue. Clear water, the two wrecks visible on the white sand from the surface. Schools of snapper, clownfish clowning about their sheltering anemone, a moray eeling through the wreckage, looking for a snack. And there he comes — like a Mandarin warship with banners flying, lances at the ready, making stately progress along the sand. Pterois Volitans, also known as the lionfish, is a magnificent creature, well-able to defend itself against most enemies with its long, poisonous spikes. I have seen it feed on shrimps herded with its long fins.

So what is the problem? While well known in the Indian and Pacific oceans, these fish had not been described in the Atlantic. Until relatively recently, that is. A few were noted off Florida, and then further afield.

A whole industry of discriminatory articles have sprung up denigrating and vilifying this poor fish. Scientists seek funding for diving trips to the Bahamas to research this invader. It threatens, they say, to destroy the reefs. Diver's wisdom is slightly different. In the Indian Ocean lionfish are well-integrated into the ecology, and so, I am told, in the Pacific. None of the reefs I know, and have dived on in Mauritius, South Africa and the South Pacific were destroyed. So why would the Caribbean reefs be endangered?

A problems is that the natural predators of the Caribbean reefs, such as groupers, are overfished and so are no threat to the lionfish. And while some scientists suggest that the aliens were introduced from aquaria in Florida it was only a matter of time before some larvae would find their way around the Cape of Good Hope or in a ship's ballast tanks through the Panama Canal.

So while this immigrant now becomes a favorite among spear fishermen and emergency room staff who have to treat spearfishermen for venomous stings, there is a much more dangerous enemy: Acanthaster planci, the crown of thorns starfish.

This beast feeds on living coral, and on reefs that were pristine two decades ago I have seen up to twenty, including numerous small ones. They are breeding. Divers try to kill them, and video shows Titan triggerfish coming to feast where an acanthaster is turned upside down.

Nature is complex and dynamic and so is the ocean. Humans are an invasive species in much of the natural habitat. Humans have interfered in the oceans, irretrievably so. Encouraging spear fishing by rich tourists where local populations keep poverty at bay by over-exploiting their only resource does not feel right. A balanced view and open mind is recommended.