[3][n 1] The ecology of Lough Melvin, and other Irish waterways, remain threatened by curly waterweed, zebra mussel, and freshwater clam invasive species.

Lough Melvin is home to the gillaroo or Salmo stomachius, a species of trout which eats primarily snails.

Fly-fishing with a team of wet flies fished in classic lough style (i.e. short, snappy casts from a boat drifting beam-on to the breeze) gives best chance of success.

[9] The classic work carried out by Andrew Ferguson of Queens University on the genetics of the trout of Lough Melvin identified the ferox as a separate subspecies.

Ferox cannibalise brown trout (which returned to many of the same lakes when geological processes and climatic conditions allowed) and also prey on other fish species.