Cloudy white / grey — new tank
This looks like: bacterial bloom while biology finds its balance — ugly, often normal, not magic evil slime
Why this happens
Bacteria that eat dust and food explode before your nitrogen team is fully staffed. That haze is biomass in the water column, not necessarily poison by itself.
What to do right now
- Test ammonia anyway — bloom plus ammonia hurts.
- Feed lightly — almost boringly light.
- Avoid cleaning the filter spotless — seed bacteria live there.
- Small water changes only if ammonia demands — massive water swaps rarely erase blooms faster.
- Patience plus test discipline — log numbers in App-aquatic so you see the curve.
What not to do
- Don’t buy “instant cycle” hope in a bottle without reading ammonia daily for a week.
Stop it happening again
Cycle the tank before adding many fish, feed lightly at first, and resist over-cleaning the filter - the bloom clears as the biology matures.
If that doesn’t fix it
Green instead of white? That is algae, not this bloom.
Catch this earlier next time — log your water parameters in App-aquatic. Free forever.
This isn't veterinary advice - it's a directional read to help you decide your next step, based on the most common causes. We can't see your fish, so pair it with a liquid test kit and clear photos, and see an aquatic vet or a trusted local fish shop for a valuable or seriously ill fish.