1. Brown Trout (Salmo trutta): This is a popular game fish in River Ouse, known for its hard fight and delicious flesh.
2. Rainbow Trout (Oncorhynchus mykiss): Rainbow Trout is a non-native species introduced in River Ouse, but it has established a strong presence and is now a popular sport fish.
3. Grayling (Thymallus thymallus): Grayling is another sought-after game fish in the river, known for its unique dorsal fin with colorful spots.
4. Chub (Squalius cephalus): Chub is a common fish in River Ouse and can be found in various stretches of the river.
5. Dace (Leuciscus leuciscus): Dace is another widely distributed fish species in the river and can be found in shoals near the bottom.
6. Roach (Rutilus rutilus): Roach is a common cyprinid fish found in River Ouse and is known for its silvery appearance.
7. Bream (Abramis brama): Bream is a large-bodied fish found in the river and is a popular target for anglers due to its fighting ability and tasty meat.
8. Pike (Esox lucius): Pike is a predatory fish found in River Ouse and is considered one of the top predators in the river's ecosystem.
9. Perch (Perca fluviatilis): Perch is a colorful fish with reddish fins and can be found in various parts of the river.
10. Eel (Anguilla anguilla): Eels are migratory fish and are found in River Ouse, but their numbers have declined in recent years due to various factors.