Stocking density is how many fish you keep per square metre. Get it wrong and you get slow growth, disease and deaths. The right number depends on your water system — a still earthen pond and a well-aerated tank are not the same.

Ponds vs tanks

Earthen ponds rely on natural balance and hold fewer fish. Concrete or tarpaulin tanks with good water exchange and aeration can hold more — but only if the water stays clean and oxygenated.

A practical guide (fingerlings to grow-out)

  • Earthen pond, low input: about 5–10 fingerlings per square metre.
  • Earthen pond, managed and fertilised: about 10–20 per square metre.
  • Concrete/tarpaulin tank with aeration: start around 30–50 fingerlings per square metre, then reduce as they grow.
  • Nearing table size: thin down to roughly 20–30 per square metre in tanks.

Thin as they grow

The key practice is to stock more at the fingerling stage, then thin — sort by size and separate or sell as the fish grow. A density that's fine for fingerlings becomes overcrowded for table-size fish.

Why overcrowding costs you

Too many fish means less oxygen, more waste, slower growth and more disease. It's the most common way new catfish farmers lose a batch. See the catfish beginner's guide for the full picture.

Key takeaways

  • Ponds hold fewer fish than well-aerated tanks.
  • Rough guide: 5–20/m² in ponds; 30–50/m² in aerated tanks.
  • Thin (sort/sell) as fish grow toward table size.
  • Overcrowding = less oxygen, slower growth, more disease.