In Spain, no one can hear you scream: Mediterranean fish under threat from gruesome 'Alien' parasite which eats their tongues then lives in their mouths

Named ¿Betty¿ by the scientists, ceratothoa italica breeds by entering the mouth through the gills. A female parasite will then take up position on the tongue, virtually replacing it, and feeding on blood as it grows to adulthood 

 A gruesome ‘Alien-like’ parasite which eats the tongues of bream and then 'replaces' them in its victims mouths is spreading in the Mediterranean.
Almost half the fish in some areas are infected with the parasite, which swims in through the gills of young fish, then takes up position on top of the tongue, feeding on blood and growing.
Researchers found that the 'cerathotoa italica' parasite - named 'Betty' by the scientists - is spreading fastest in heavily fished waters.

A fully-grown 'Betty' parasite in the mouth of a striped bream. In heavily fished areas, nearly half of fish are affected by the parasite 

Though the parasite poses no risk to humans, it stunts the growth of the fish, and lowers their life expectancy.
The researchers found that 'Betty' thrived in overfished areas. In a protected area near Spain, only 30% of fish were infected - in heavily fished Italian waters, 47% had fallen victim to the parasite.
Dr Stefano Mariani of the University of Salford said: ‘This is further evidence that human over-exploitation of fish stocks has adverse and far-reaching effects.  Areas with poor regulation have smaller, younger fish and, as we’ve now demonstrated, higher and more harmful parasite infestations.'


‘Betty is quite gruesome and does remind you of the Alien films, but it’s a highly adapted and specialised animal which is very successful.  Unfortunately, over-fishing upsets the balance of parasite and host and interferes with the whole eco-system.
‘It makes a lot of sense for protected areas to be established so we can safeguard both the quantity and the quality of the fish we eat.’


Salford’s Dr Stefano Mariani and colleagues from University College Dublin and the University of East Anglia inspected stocks of striped sea bream in two areas of the Mediterranean - a Spanish area protected from fishing and heavily fished Italian waters.

The researchers also found that the parasite had worse effects on fish from heavily fished areas - while the parasite infection sigthnificantly stunted growth and condition in the Italian fish, it had no detectable effects on the physiology of the Spanish ones.