Common Aquarium Fish Diseases in India: Symptoms & Treatment
How to identify ich, fin rot, dropsy, swim bladder problems, fungus and velvet, and treat them with salt baths and medicines you can actually buy in India.
Almost every fish disease you will meet is triggered by the same two things: poor water quality and stress. Learn to spot the early signs and most outbreaks are treatable; wait until a fish stops eating and lies on the bottom, and your options shrink fast. This guide covers the six diseases Indian hobbyists see most, with treatments using medicines actually available in Indian shops and online.
Quick Reference: Symptoms and First Response
| Disease | Key Symptoms | First Response |
|---|---|---|
| Ich (white spot) | Salt-grain white dots on body and fins, flashing (rubbing on objects) | Raise heat to 30°C, add aquarium salt, medicate |
| Fin rot | Ragged, milky or blackened fin edges that recede over days | Big water change, clean water, antibacterial medicine if it advances |
| Dropsy | Swollen belly, scales sticking out like a pinecone | Isolate, Epsom salt bath, antibacterial food; often fatal, act early |
| Swim bladder disorder | Floating upside down, sinking, or struggling to stay level | Fast 2-3 days, then feed a shelled, blanched pea; check water |
| Fungus | Cotton-wool white tufts on body, mouth or fins | Remove cause (injury, dirty water), treat with methylene blue |
| Velvet | Fine gold or rust dust on skin, clamped fins, scratching | Darken the tank, raise heat, copper-based or general anti-parasite medicine |
Ich (White Spot Disease)
Ich is a parasite that shows as distinct white grains, like the fish was sprinkled with salt. It spreads fast in a stocked tank, especially after adding new fish without quarantine or after a temperature drop. Treat the whole tank, not just the spotted fish: raise the temperature gradually to 30°C to speed the parasite life cycle, add aquarium salt at 1 to 2 grams per litre (skip salt with scaleless fish like loaches), and dose a malachite green and formalin based medicine. In India, Rid All General Aid, API Super Ick Cure, and Ocean Free anti-ich treatments are widely available for ₹100 - ₹400. Continue treatment for 3 days after the last spot disappears.
Fin Rot
Fin rot is a bacterial infection that eats fin edges, most common in bettas, guppies, and goldfish kept in dirty or overcrowded water. Mild cases heal with water quality alone: a 40 to 50 percent conditioned water change, gravel vacuuming, and daily small changes for a week. If the rot keeps advancing or reaches the fin base, treat with an antibacterial such as API Fin & Body Cure, Melafix, or a vet-guided antibiotic. Fins regrow in 2 to 4 weeks once the infection stops.
Dropsy and Swim Bladder Problems
Dropsy is not a disease but a symptom of internal organ failure, usually bacterial: fluid builds up until the belly swells and scales stand out like a pinecone. Isolate the fish in a hospital tank, add Epsom salt (magnesium sulphate, sold at any Indian pharmacy) at 1 to 2 grams per litre to help draw out fluid, keep the water pristine, and offer antibacterial food. Be honest with yourself: full pinecone dropsy is usually fatal, and early isolation protects the rest of the tank.
Swim bladder disorder, common in fancy goldfish and bettas, shows as floating, sinking, or swimming tilted. The usual cause is overfeeding or gulped air with floating food. Fast the fish for 2 to 3 days, then feed a single shelled, blanched green pea; switch to sinking pellets and pre-soak dry food. If it persists, treat water quality and consider internal bacterial infection.
Fungus and Velvet
True fungus grows as white cotton-wool tufts, almost always on an injury or on fish weakened by bad water. Methylene blue is the classic treatment, cheap and available at every Indian aquarium shop; use it in a hospital tank because it stains silicone and kills filter bacteria. Velvet is subtler and deadlier: a dusting of fine gold or rust powder, best seen under torchlight, with clamped fins and rapid breathing. The parasite uses light, so dim the tank, raise the temperature to 29-30°C, and treat with a copper-based medicine or a general external anti-parasite treatment, removing carbon from the filter first.
Salt Baths: The Cheapest Medicine
- Use plain aquarium salt or non-iodised crystal salt, never table salt with additives.
- For an in-tank tonic dose: 1 to 2 grams per litre, dissolved in a mug of tank water before adding.
- For a short bath: 10 grams per litre in a separate bucket of conditioned, temperature-matched water; keep the fish in for 5 to 10 minutes, watching constantly.
- Remove the fish immediately if it rolls over or gasps heavily.
- Never salt-dose tanks with loaches, catfish or other scaleless fish, and remember live plants dislike salt.
Prevention Beats Every Medicine
- Quarantine every new fish for 2 weeks in a separate tank before adding it to your display; this alone prevents most outbreaks.
- Do weekly 25 to 30 percent water changes with conditioned water; chlorinated Indian municipal water must always be treated.
- Do not overfeed: uneaten food is the number one cause of the water conditions that trigger disease.
- Keep temperature stable; sudden drops during winter nights or power cuts commonly trigger ich.
- Buy from clean, well-maintained sources. Healthy stock from a trusted seller like Kolathur Fish Market beats treating cheap sick fish every time.