🐟 Freshwater Fish

Quick Answer: Most freshwater fish need a cycled tank, stable temperature (72–78°F), pH 6.8–7.4, and weekly 20% water changes. Match fish to your tank size — most "beginner fish" still need at least 20 gallons for a proper community.

Species care guides for freshwater aquarium fish — covering tank requirements, water parameters, diet, breeding, and compatibility for each species.

Frequently Asked Questions: Freshwater Fish

How many fish can I keep in my tank?

The old "1 inch per gallon" rule is unreliable — it doesn't account for fish shape, bioload, or behavior. A better approach: look up the specific requirements for each species, consider their adult size, and use our Tank Size Calculator to estimate stocking density based on actual fish bioload.

Why do my fish keep dying?

The most common causes: ammonia or nitrite toxicity from an uncycled or crash-cycled tank, temperature swings, pH swings, overfeeding, and disease introduction from new fish without quarantine. Test your water first — most fish deaths can be traced to water chemistry problems.

Do I need a heater for freshwater fish?

Most tropical freshwater fish need water between 72–82°F (22–28°C) and require a heater unless your home stays consistently warm. Only goldfish, white cloud mountain minnows, and a few other cold-water species do well at room temperature.

How often should I feed my freshwater fish?

Once or twice daily is standard for most species — feed only what they consume in 2–3 minutes. Overfeeding is the most common mistake: uneaten food decomposes and spikes ammonia. Most fish can go 3–5 days without food without harm.