Cloudy water in a shrimp tank: bacterial bloom or something else?

A white or milky haze can fit suspended bacteria, but appearance alone cannot confirm this. Dust after substrate disturbance, tiny bubbles and other suspended particles call for different responses. Assess the animals and water measurements first, then how the haze began.

Collect three clues

• Timing: did it begin immediately during filling, after substrate work or maintenance, or later? Record additions and changes in filter flow.
• Appearance: can you see separate particles, rising bubbles, a green tint or uniform haze? Examine a sample in a clean transparent container reserved for this purpose. This aids description, but is not a microbiological test.
• Effect: are the shrimp functioning normally? Test temperature, ammonia and nitrite. For group distress, surface behaviour or loss of balance, immediately follow the gas-exchange route.

Clear water and suitable water are different things

Decomposing organic material can consume oxygen. Leftover food, dying plants and disrupted filtration are therefore relevant investigation points. Haze does not establish the presence of ammonia; conversely, clear water can have unsuitable readings. Suspended bacteria also do not establish that the biofilter can process enough ammonia and nitrite.

Address the load you actually find

Remove identifiable leftover food and loose decaying material without disturbing the entire substrate. Check filtration and surface movement. If mechanical media are blocked, restore flow selectively while preserving biological filtration. Replacing the whole filter to clear the tank can introduce another problem.

Base water changes on measured or suspected contamination and replacement-water suitability, rather than a mandatory small amount or a fixed wait in days. The water-choice guide helps assess source water and changes.

Do not use an antibacterial product solely to make haze disappear. Recheck behaviour, flow and relevant measurements even after the water clears. If the cause remains uncertain or animals become ill, seek a targeted water and animal assessment. In a new unstocked tank, do not introduce shrimp while the haze or filtration capacity remains unexplained.

Sources and scope

• US EPA: Dissolved oxygen
• UF/IFAS: Ammonia in Aquatic Systems
• Merck Veterinary Manual: Environmental Diseases of Aquatic Animals

The sources explain oxygen demand and nitrogen processing. Comparing dust, bubbles and persistent haze is an editorial observation route. We do not identify a bacterial species or guarantee a cause without further investigation.