Prevention and Treatment of Hydrogen Sulfide Exposure
2026-06-05
Hydrogen sulfide is a soluble, toxic gas with the characteristic odor of rotten eggs. Among the many factors that influence aquaculture success, hydrogen sulfide is one of the most harmful yet often overlooked; it has increasingly become a critical limiting factor in achieving successful farming.
Causes of hydrogen sulfide formation:
Sulfides in aquatic environments are produced through the anaerobic decomposition of organic matter over time, under the combined influence of specific water temperature, pH, concentration, and oxygen‑deficient conditions. In aquaculture, this process is primarily affected by the following two key factors:
- Humus, an organic substance produced by the decomposition of certain plankton and aquatic animals after their death.
- Residual feed and feces—unreasonable feeding practices result in substantial leftover feed, while the excrement produced by farmed animals is not removed promptly.
Hazards of Hydrogen Sulfide Hydrogen sulfide can penetrate and be absorbed into the tissues and bloodstream of aquatic animals, where it binds to oxygen‑carrying proteins, disrupting their structure and impairing their ability to transport oxygen, thereby manifesting as hypoxic symptoms. The harmful effects of hydrogen sulfide on cultured species are evident even at low concentrations: initial responses include reduced digestive capacity and decreased feed intake, followed by weakened physical condition and diminished immunity, making the animals more susceptible to pathogenic infections, leading to hypoxic surfacing and sudden mortality.
Symptom presentation
Acute poisoning: Mass mortality within a short period (particularly among benthic organisms), with blackened, congested gills, increased mucus on the body surface, and hepatic lesions.
Chronic hazards: reduced feed intake, slowed growth, impaired immunity, and increased susceptibility to secondary infections.
Prevention and response measures for hydrogen sulfide:
- Strong aeration; apply oxygen tablets (sodium percarbonate, calcium peroxide) in large quantities to the pond bottom to increase dissolved oxygen at the lower layer.
Chemical oxidation: potassium ferrate and persulfates can directly oxidize and decompose.
Hydrogen sulfide in the sediment improves bottom‑water quality with rapid results (note: dosage and dissolved oxygen levels must be carefully monitored).
Going forward, regular bottom‑conditioning treatments are required for maintenance and prevention; we recommend periodic use of the biological bottom conditioner—Zhongren Di Liu Qing (fecal sulfur‑degrading bacteria).
Zhongren Bottom Sulfur Clear has undergone rigorous screening to identify key strains, including hydrogen sulfide‑oxidizing bacteria, which can break down organic matter at the pond bottom, prevent hydrogen sulfide accumulation, and loosen the sediment, thereby providing an indirect aeration effect. Below are experimental results comparing Zhongren Bottom Sulfur Clear with products from other manufacturers.
Real-life case:
Location: Xinhu Town, Dongying City
Date: June 7, 2025
Cultivation area: 150 mu
Species: Whiteleg Shrimp
Due to tight schedules this year, farmers failed to drain and dry the ponds, resulting in blackened pond bottoms, thick sludge buildup that continues to worsen, and occasional bubbling. Downwind areas exhibit a faint odor of rotten eggs, and the water quality has deteriorated. Preliminary assessment indicates that bottom‑water degradation is driving hydrogen sulfide production. Testing confirms the presence of low levels of hydrogen sulfide, though the situation remains relatively mild.
Handling plan:
That evening, we increased the dosage of Zhongren Bottom Sulfur Clear (75 mu per bag) and applied it directly to the entire pond, using a total of 50 kg for 150 mu. 
On the second day after use, no bubbles were observed at the bottom of the pond, and the hydrogen sulfide concentration was measured to be zero.
By the third day of use, the water color has improved, with noticeable clarity, leaving you feeling refreshed.
Within the following month, a farmer visited the store and reported, “Since this small pond was relocated, it has been performing excellently. Today, I plan to take some more Ditiqing to apply to my other ponds.”
Prevention is better than cure; regularly test water quality and closely monitor the health of your shrimp to nip problems in the bud.
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Qingdao Zhongren Animal Medicine Co., Ltd
Zhongren Aquatic Products