The ethics of fishkeeping

Why ethics matter

Fish are sentient animals. Ethical fishkeeping means giving them a life that meets their needs — space, water quality, companionship where appropriate, and a stable environment. It also means thinking about where fish come from and how our choices affect wild populations and the trade.

Give them enough space

One of the most important ethical choices is tank size. Fish do not grow to tank size — they grow to their genetic potential, and cramped conditions cause stunting and stress. Use our tank size calculator or stocking calculator before buying. Avoid overstocking. A bigger tank is often easier to maintain and better for fish.

Research before you buy

Know the species: adult size, temperament, group size, and water needs. Compatibility matters — mixing incompatible fish causes stress or injury. Avoid impulse buys. Use how to use a stocking calculator and breeding to plan for fry if you keep livebearers.

Cycle your tank first

Adding fish to an uncycled tank exposes them to ammonia and nitrite, which burn gills and cause suffering. Cycle your tank before adding fish. Fishless cycling avoids putting fish through a cycle crash.

Source fish responsibly

Choose captive-bred when possible — it reduces pressure on wild populations and often produces hardier fish. See our wild caught vs captive bred guide. Buy from reputable shops or breeders who keep fish in healthy conditions. Ask about origin and quarantine.

Quarantine new fish

Quarantining new fish protects your existing stock from disease and parasites. It also gives you a chance to observe and treat new arrivals before they join the main tank.

Maintain water quality

Stable, clean water is the foundation of welfare. Track parameters, do regular water changes, and avoid overfeeding. Use App-aquatic to log tests and reminders so nothing slips.

Plan for the long term

Fish can live for years. Before you buy, decide who will care for them if you move, travel, or can no longer keep them. Rehoming is better than neglect. See moving house with an aquarium for practical steps.

Quick takeaways

• Give enough space; research before buying.
• Cycle first; avoid impulse buys.
• Source responsibly; quarantine new fish.
• Maintain water quality; plan for the long term.