The Walking Catfish, Running Large Risks in Florida?

Hi everyone, happy new year! There's been some decent TV on over the past couple of weeks with new episodes of Sherlock and Dr Who causing excitement for millions. For me, however, the highlight of the winter TV season came on Wednesday during Nature's Weirdest Events.

About two minutes in, Chris Packham starts talking about some unusual events that have taken place in Florida. It seems there have been fish casually walking about on land, as if it's where they belong... Check out the link above for the footage and humorous commentary from astounded Americans.

A walking catfish, out on the land.

According to Packham, the fish normally appear on land after storms, and their numbers are increasing yearly to what now amounts to a very high population.

But how can these catfish even survive on land, let alone walk on it? Well, it seems they have a special organ allowing it to take oxygen from the air. Handy, huh? And they can walk, thanks to their pectoral fins and tail, in the manner of a commando crawl. They can also survive several months without food.

Thanks to these adaptations, the fish have been causing numerous problems. And guess what? They're an invasive species! And listed as one of 100 of the worst invasive species at that (Lowe et al., 2000).

The catfish is native to Southeast Asia, but was imported to Florida in the 1960s by aquaculture farmers (National Geographic). Within 10 years, the fish had spread significantly within the state.

Worldwide walking catfish distribution...

... and the spread of the walking catfish in Florida. Source: Columbia.edu

A tropical fish farmer describes how he used to have 10,000 Rosy Barbs, but now, as a result of ferocious predation, all his pond seems to contain are walking catfish! It seems they move from pond to pond, making use of their unique adaptations, wiping out all the tropical fish. Sad.

Additionally, the invasion has happened quickly, so native wildlife has had little time to adapt and is suffering as a result. The walking catfish feed on other fish, invertebrates, amphibians and aquatic insects. The devastation is described as 'tremendous'. Damage caused by the walkers has cost millions of dollars (National Geographic).

All hope is not lost though. The walking catfish is predated by wading birds including herons and egrets, which means fewer native species are threatened than they otherwise would be.

Even so, it seems the walking catfish is running large risks to Floridian freshwater ecology.

Over and out

The Invader Inspector