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AquariumSOS

Diagnose fish problems, plan your tank, keep everything alive.

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Free Tools

No AI guesswork — structured diagnostics built from real symptom and cause data across 268+ species.

Diagnose Your Fish

Answer a few questions about symptoms and behavior and get 2-3 ranked likely causes, not a guess.

Compatibility Checker

Check whether species you're considering will actually get along in one tank.

Stocking Calculator

Bioload-based stocking guidance for your tank size — not inch-per-gallon myths.

Water Parameter Guide

Ideal ranges per species, plus a plain-language read on your own test results.

Fish Species Guides

Betta Fish Goldfish Guppy Neon Tetra Angelfish Molly Fish Platy Fish Swordtail

Disease Library

Ammonia Poisoning in Fish — Recognizing and Reversing It Before It's Fatal Anchor Worms (Lernaea) — The Parasite You Can See and Physically Remove Bacterial Infections in Fish — Recognizing the Common Patterns Brooklynella (Clownfish Disease) — A Fast, Dangerous Parasite Disproportionately Affecting Clownfish Camallanus Worms (Red Worm Disease) — The Parasite Visible at the Vent Columnaris (Cotton Wool Disease) — A Fast-Moving Bacterial Infection

Browse by Category

Aggressive Fish Algae-Eating Fish and Invertebrates Beginner-Friendly Fish Bottom-Dwelling Fish Brackish Water Fish Fish That Can Live Alone

From the Blog

Types of Aquarium Algae: Identification and Fixes for Each

How to identify green dust, brown diatoms, black beard algae, hair algae, and cyanobacteria, and the specific cause-driven fix for each rather than a one-size-fits-all treatment.

Choosing Your First Fish Tank: Size, Shape, and Placement

Why a bigger first tank is usually easier, not harder, plus how tank shape affects stocking and where in the house a tank actually belongs.

How to Stock a Community Tank Without Overcrowding or Fighting

A practical framework for planning a peaceful community aquarium: understanding bioload versus the one-inch-per-gallon myth, matching temperament and water-level niches, and stocking order.