Bert Willaert / Composite image of American fish species introduced to Europe: Pumpkinseed sunfish (Lepomis gibbosus, left), Brown bullhead (Ameiurus nebulosus, right) and Eastern mudminnow (Umbra pygmaea, under), ph...

MYN / Krista Schlyer / Brown bullhead (Ameiurus nebulosus), Anacostia watershed, Washington DC, USA, April. Meetyourneighbours.net project.

MYN / Krista Schlyer / Brown bullhead catfish (Ameiurus nebulosus) Anacostia River, Washington DC, April. Meetyourneighbours.net project

MYN / Krista Schlyer / Brown bullhead catfish, (Ameiurus nebulosus) Anacostia River, Washington DC, April. Meetyourneighbours.net project

Alex Mustard / Red Irish lord (Hemilepidotus hemilepidotus) hides on the seabed, with Quillback rockfish (Sebastes maliger) and copper rockfish (Sebastes caurinus) behind in the bull kelp forest. Browning Pass, Vanc...

Juan Manuel Borrero / Illustration of threatened species of Spain : Blue whale (Balenoptera musculus), Brown bear (Ursus arctos), Spanish ibex (Capra pyrenaica hispanica), Bullhead (Cottus gobio), Iberian Rock Lizard (Lace...

Alex Mustard / Red Irish lord (Hemilepidotus hemilepidotus) camouflaged on reef with White short plumose anemones (Metridium senile), Browning Pass, Vancouver Island, British Columbia, Canada, Queen Charlotte Strait...

Alex Mustard / Red Irish lord (Hemilepidotus hemilepidotus) camouflaged amongst Red soft coral (Eunephthya rubiformis) and Yellow encrusting sponges (Myxilla lacunosa) with White plumose anemones (Metridium senile)...

Shane Gross / Shorthorn sculpin (Myoxocephalus scorpius) hiding in Kelp. Terra Nova National Park, Newfoundland, Canada. May.