Goldfish Aggression in a Small Tank: Breeding, Boredom, or Bullying?

Why Your Fantails and Comet Are Chasing Each Other

Three goldfish in a 14-liter tank (≈3.7 gallons) is severely overcrowded. The chasing you see is likely a mix of:

1. Spawning Behavior

Even young goldfish (3–4 inches) can develop breeding tubercles and chase females relentlessly. The comet's speed makes it a persistent pursuer.

2. Territorial Stress

In tiny volumes, fish establish dominance hierarchies through chasing.

3. Boredom

Bare tanks offer no enrichment.

Solutions

1. Upgrade immediately – 75+ gallons for three goldfish.
2. Add hiding places – dense plants (anacharis, hornwort), PVC tubes, caves.
3. Separate the aggressor – if one fish is the primary bully, a temporary timeout in a breeder box can reset dynamics.
4. Enrich – vary diet, add floating veggies, rearrange decor weekly.

Long-term, only a proper tank will stop the chronic stress and injury.