Dropsy in Pond Fish: Causes, Contagion, and Supportive Care

What Is Dropsy?

Dropsy (pinecone scales, bloating, odd swimming) is a *symptom* of internal organ failure—usually kidney or liver—caused by opportunistic bacteria (Aeromonas, Pseudomonas) that are always present in ponds. It's not a primary disease you "catch."

Is It Contagious?

The bacteria are ubiquitous. Other fish are already exposed. They only develop dropsy if *their* immune system is compromised by stress, poor water quality, or injury. Treating the whole pond with antibiotics is rarely justified and harms the biofilter.

Action Plan for Affected Fish

1. Quarantine the sick fish in a hospital tank with clean, aerated water.
2. Test main pond water: pH, KH, ammonia, nitrite, nitrate. Fix any issues.
3. Do a 25% water change in main pond with dechlorinator.
4. Add pond salt at 0.05% (0.5 lbs per 100 gal) to reduce osmotic stress.
5. Add beneficial bacteria (KoiZyme, Microbe-Lift) to lower pathogenic bacterial load.
6. In hospital tank: MelaFix (antiseptic), salt 0.3%, and *if a vet is available*, injectable Baytril (enrofloxacin). Oral antibiotics are poorly absorbed.

Prognosis

Dropsy is rarely curable once scales pinecone. Euthanasia (clove oil overdose) is often the kindest option. Focus on preventing the next case by optimizing water quality and reducing stress.