

Adult flatfishes (soles, flounders, etc) are bottom-living fishes which are easily recognised by their laterally flattened bodies with both eyes on the one side of the head.
All adult flatfishes go through a larval phase. For at least part of this phase, the developing flatfish looks more like a "normal" fish. It swims in open water with its back uppermost and has eyes on either side of the head. The top image is a 4.0mm larval sole with its fins starting to develop, and one eye on either side of the head.
The lower image shows a 11.6mm larval sole. By this size the sole has started to look more like an adult flatfish. The fins have developed, and the left eye has moved over the snout onto the right side of the head.