Aquarium intelligence for healthier, better-understood aquariums
Structured, sourced intelligence on aquarium organisms, plants, water chemistry, compatibility and problems — with the evidence behind each value and the uncertainty shown rather than smoothed away.
Start here
- Find a speciesAdult size, water requirements, group needs, behaviour and what the shop label leaves off.235 fish · 71 invertebrates
- Check compatibilityExplainable assessments derived from stored traits — concerns, conditions and confidence, not a yes/no chart.Any pair in the catalogue
- Understand your waterThe nitrogen cycle, ammonia and pH, GH against KH, buffering, oxygen and CO₂ — precise, with the qualifications kept in.25 concepts
- Diagnose a problemStart from what you can see. Each problem lists the plausible causes and what observation separates them.28 problems
- Explore plantsLight, CO₂ and nutrient requirements — and how to install each one without killing it.78 species
- Use a calculatorVolume, water change, heater sizing, turnover, free ammonia and unit conversion. Every formula shown.10 tools
Something is wrong right now
Test ammonia, nitrite and nitrate first, and check the temperature with a thermometer you trust rather than the heater dial. These four cover most emergencies.
- Fish gasping at the surface5 possible causesGasping means the fish cannot get enough oxygen into its blood. That can be because there is too little oxygen in the water, or because the gills or the blood have been damaged — most often by ammonia or nitrite. Test the water first.
- Ammonia detected in the tank5 possible causesAmmonia above zero in a stocked tank means production has outrun the filter. Change water now, stop feeding, and then find out why — because the reading is the symptom, not the cause.
- Fish dying in a new tank4 possible causesIn a tank under about three months old, the overwhelming probability is that it was not cycled. Test ammonia and nitrite before considering anything else.
- pH has crashed4 possible causesA pH crash means the carbonate buffer ran out. Test KH — if it is at or near zero, that is the whole explanation, and the fix is to restore buffer gradually rather than to add a pH-up product.
Aquarium science, properly explained
Most water advice in circulation is a simplification of a simplification. Each of these keeps the qualifications that usually get trimmed off.
What is in here, and what is not
306 organisms, 78 plants, 25 water concepts, 28 troubleshooting paths, 22 equipment concepts and 26 comparisons, drawn from 35 registered sources. There are no product rankings, no affiliate links, and no health condition pages — the last of those is a deliberate gap, because health content without veterinary sourcing is the most harmful thing this product could publish.
Everything missing is listed on the coverage page, along with every candidate page the opportunity engine refused to build and why.