Fat Goldfish: Pregnant, Dropsy, or Overfed? Plus Green Water Fix

Four "pregnant" goldfish and chronic green water? The swelling is likely not eggs, and the green water shares the same root cause: excess nutrients from overfeeding or poor biological balance.

Diagnosing the Swelling

Condition	Appearance	Key Signs
Gravid (eggs)	Slight, symmetrical swelling behind ventrals	Spawning behavior (chasing), seasonal (spring), scales flat
Dropsy	Global bloating, pinecone scales	Scales stick out, lethargy, often fatal, bacterial/kidney origin
Kidney failure	Slow, massive enlargement	No pineconing initially, fluid accumulation, scales may stretch
Cysts/tumors	Localized lumps	Asymmetric, may be fluid or solid
Overfeeding/constipation	Temporary belly distension	Reduces with fasting, normal behavior otherwise

Why Four Fish at Once?

Multiple affected fish suggests a shared environmental cause: poor water quality, overfeeding, or contagious bacterial issue. Test ammonia, nitrite, pH, KH immediately.

Green Water = Nutrient Imbalance

Nutrients IN (food, waste, tap water) > Nutrients OUT (plants, bacteria, water changes) = Algae bloom

Fix Both Problems Simultaneously

1. Stop feeding completely for 2–3 weeks. Fish eat algae, biofilm, insects. Swelling from overfeeding will resolve.
2. Add gravel substrate (1–2 inches large gravel) for bacterial colonization.
3. Run pump 24/7 at 1× pond volume/hour minimum.
4. Add concentrated bacteria (Microbe-Lift PL, etc.) per label.
5. Add floating plants (hyacinth, lettuce, frogbit) covering 50–70% surface.
6. No water changes unless ammonia/nitrite spike. Changes add nutrients and disrupt bacteria.
7. Test water daily until ammonia/nitrite = 0.

If Dropsy Is Confirmed

• Isolate affected fish if possible (easier to treat in small volume).
• Pond salt 0.1% (no plants) or 0.05% (with plants).
• Antibiotics: erythromycin (Maracyn) or vet-injectable.
• Prognosis is guarded—dropsy is often fatal.

Don't Separate Unless Necessary

Dropsy bacteria are ubiquitous. Quarantine helps treatment but doesn't protect pond mates—they're already exposed.

Fix the ecosystem, and both problems often resolve together.