The fish with pseudo-eggs on their faces

US scientists have discovered six new species of “really cool catfish” in South America’s Amazon and Orinoco River basins.

That may sound like high praise for things with faces covered in tentacles, spines sticking out of their heads and bony plates like armour on their bodies, but there is some basis to the description.

The cool bits are the tentacles, which males use to convince females that they would make good dads.

All six new species are members of the genus Ancistrus (also known as bristlenose catfish), and it’s the fathers that look after their young, guarding nests of eggs and warding off predators.

“The idea is that when a female fish sees a male with these tentacles, to her, they look like eggs,” says conservation scientist Lesley de Souza from Chicago’s Field Museum.

“That signifies to her that he’s a good father who’s able to produce offspring and protect them.”

The new discoveries, which de Souza and colleagues describe in a paper in the journal Zootaxa, are between seven and 15 centimetres long.

The catfish are found in northeastern South America, in an area of Venezuela, Colombia and Guyana known as the Guiana Shield, where they live in clear, fast-moving rivers and streams.

“If you’re in the right habitat, you’re going to find a lot of them,” says de Souza. “But they are sensitive to subtle changes in the environment. We have seen this at sites where they were plentiful and now scarce; this is due to habitat destruction.”

And as in so many parts of the world, that’s an issue for more than just the catfish.

“The whole ecosystem is interconnected; you can’t separate the species in it,” notes de Souza.

She suggests “discovering new species and putting names on them” is an important part of saving areas such as the Amazon:

“Everything begins with naming a species and determining how many species you have. Once you have done the taxonomy then you can study the ecology, behaviour, and do conservation action.”

“For example, Ancistrus kellerae is a species only known from the highlands in Guyana. There are current threats to its ecosystem by gold mining, but now that is has a name, we can try to push for conservation protection of the area with this endemic fish species.”