Summer is the danger zone
AgriLife fisheries specialists warn that July and August can be deadly for fish if dissolved oxygen drops. Warm water holds less oxygen, and several hot, still, cloudy days in a row slow the photosynthesis that replenishes it.
A cold thunderstorm can also flip a stratified pond — mixing oxygen-starved bottom water into the top layer — and kill fish within a day or two.
Warning signs
- Fish gulping at the surface near daybreak, when oxygen is lowest
- Fish suddenly ignoring feed
- Water turning from green or clear to brown or black
- Heavy vegetation — AgriLife attributes about 80% of low-oxygen fish kills in Texas to aquatic plants
Choosing an aerator
Aeration is not required, but AgriLife calls it a good preventive investment. Specialists recommend bottom-diffuser systems over surface aerators because they mix the full water column and help prevent turnover. Run them from dusk to dawn, when oxygen is most needed.
Most stock tanks sit far from power, which is why solar-driven diffuser kits are popular on Texas acreage.