How to identify brill

Look at this first

Diagnostic — settles it on its own

Each of these settles the identification on its own. If one is clear, you have your answer.

• Smooth upper surface with no hard knobs in the skin

  Turbot carries bony tubercles scattered over the eyed side — raised, hard, unmistakable under a palm. Brill has small scales and nothing else, and the surface reads as continuous. This is the character the whole separation rests on, and it is far better checked by touch than by eye: at photograph resolution, and at the angles people actually shoot fish, tubercles that are plainly there under a hand can be invisible on a screen. If you have the fish, feel it.

Supporting — use with other characters

Real characters that are not conclusive by themselves. Use two or three together.

• An oval outline rather than a near-circular one

  Lay the fish flat and compare its length against its depth. A brill runs to something like one and a half times as long as it is deep and reads as a rounded oval. A turbot is close to as deep as it is long and reads as a disc. This is judgeable from a photograph, which is the reason to learn it, but the two ranges do touch at the margins and a single specimen near the boundary settles nothing on its own.

• Loose fringed rays at the front of the dorsal fin

  Where the dorsal fin begins, beside and slightly ahead of the eyes, the first several rays are not bound into the fin membrane but stand free, branched and slightly ragged. It is a small feature and easy to overlook, and it is genuinely present on a brill and not on a turbot. It is most visible on a fish lying flat with the fin relaxed, and least visible on one that has been in a box.

• Eyes on the left, over a sandy mottled surface

  With the fish laid flat and the eyed side up and the head towards you, the eyes are on the left. The upper surface is sandy to olive-brown with fine pale and dark flecking that changes to match whatever the fish is lying on. Left-eyedness places it with the turbots and away from plaice, dab, flounder and sole, all of which are right-eyed; it does not begin to separate brill from turbot, which are both left-eyed.

Suggestive only — varies with condition

Hints only. These vary with condition, season, water and how long the fish has been out of it, and a fish that contradicts them is still the same species.

• The weight a rod-caught fish reaches

  A good brill is a fish of a kilogramme or two and a large one is four or five. Turbot grow substantially heavier. A very large left-eyed flatfish is more likely to be a turbot and should be checked by hand rather than by outline, but a fish in the ordinary size range tells you nothing at all and the skin test still has to be made.

What it gets confused with

• Turbot, almost exclusively, over the same ground and in the same season. The bony tubercles decide it and nothing else reliably does.
• Brill and turbot hybrids, which occur where the two spawn together and which carry reduced, patchy tubercles that make the definitive test ambiguous.
• Megrim at a glance, which is left-eyed but much more elongate and thinner in the body, with a larger mouth.
• Topknots on rough ground, which are smaller, hairier at the fin margins, and unlikely to be confused once handled.

Side by side: Brill vs Turbot.

Where this stops working

The full record

This page covers identification only. The Brill record covers behaviour, lifecycle, distribution, handling and the sources behind all of it.