River Thames Fish: 115+ Species Recorded, Population Variable

Exact fish numbers are unknowable—populations fluctuate with tides, seasons, pollution, restoration. But the Zoological Society of London (ZSL) confirms ≥115 species recorded.

Common Species

• Freshwater: Carp, bream, tench, roach, perch, pike, chub, dace, barbel.
• Migratory: Atlantic salmon, sea trout, European eel, smelt, flounder, mullet.
• Estuarine/Marine visitors: Bass, sole, plaice, herring, sprat, pipefish, seahorses.
• Non-native: Zander, wels catfish, pumpkinseed, gibel carp.

Recovery Story

• 1957: Declared "biologically dead" (oxygen zero).
• 1960s–: Sewage treatment, industrial regulation, habitat restoration.
• Today: One of world's cleanest urban estuaries; seals, porpoises, sharks return.

Ongoing monitoring by ZSL, Environment Agency, citizen science.