Constrained to UK sea species
Castwise is rolled out across the UK and ready to use for shore-fishing planning wherever you fish. AI Fish ID helps you snap a photo and get a likely identification for UK sea fish, with handling guidance and clear disclaimers so you verify before you retain anything.
AI Fish ID is a Castwise feature that gives a likely identification for a UK sea fish from a photo, constrained to species you can realistically catch from UK shores. It is an estimate to help you learn, not a legal determination.
No. Fish ID can suggest the likely species and surface general handling and minimum-size guidance, but it cannot confirm whether a fish is legal to keep. Always measure the fish and check current local minimum sizes and rules before deciding.
It is designed with common UK confusions in mind — such as poor cod, pouting and whiting, or the wrasses, breams and ray species — but lookalikes are exactly where any photo ID can be wrong, so treat close calls with caution.
Castwise accepts up to two photographs, compresses them before upload and keeps enough resolution for details such as fins, barbels, mouth shape and markings. A whole-fish side view is the best first image; a second angle or close-up of the mouth, fins and tail can resolve a close call.
General image classifiers try to name any fish on Earth, which is how a UK wrasse can end up labelled as a tropical reef fish. Castwise takes the opposite approach: identification is constrained to the species you can realistically encounter on UK shores, so results stay grounded in what is actually on the end of your line.
Most misidentifications on the UK coast come from a handful of genuine lookalikes. Small round fish get muddled between poor cod, pouting and whiting. Flatfish, the various wrasses, the breams and the ray species all have close cousins. Fish ID is built with these confusions in mind and flags where a call is close — but a photo can still get lookalikes wrong, so check the distinguishing features yourself.
Castwise will only offer a size estimate when a clear scale reference is visible in the photo — a measuring mat, a marked ruler, or a known object in frame. A fish held at arm’s length towards the camera looks far bigger than it is, so without a reliable reference no size figure should be used to decide whether to keep a fish.
The service compares the leading result with plausible lookalikes. If confidence or the margin over the next candidate is too low, it returns an uncertain result and asks for better evidence instead of presenting a definitive identification. Users can correct the answer; Castwise stores evaluation metadata about that correction, not the submitted Fish ID photograph.
Where a species is identified, Castwise can surface general good-practice guidance on careful handling and returning fish you are not keeping, alongside a reminder of typical minimum sizes. This is guidance to help you fish responsibly — it is not confirmation that a fish is legal to keep, and it never replaces measuring the fish and checking the current local rules.
Castwise updates
Get Castwise to try AI Fish ID built around UK sea species — and keep an honest, private logbook that sharpens your recommendations.