Here's why your molly fish might be developing Ich:
* Stress: Overcrowding, poor water quality, sudden temperature changes, or aggression from tank mates can stress mollies and make them susceptible to Ich.
* New fish: Introducing new fish to the tank can carry the parasite, even if they appear healthy.
* Infected equipment: Nets, decorations, or other equipment can harbor the parasite and spread it.
* Poor water quality: High ammonia, nitrite, or nitrates levels can weaken the fish's immune system and make them more prone to infection.
Here's what you should do:
1. Identify the problem: Observe your mollies closely for signs of Ich. Look for white spots on their bodies, fins, and gills.
2. Improve water quality: Perform a large water change (at least 50%) to reduce ammonia, nitrite, and nitrate levels.
3. Raise the temperature: Raise the tank temperature to 82-86°F (28-30°C). This slows the Ich parasite's lifecycle and helps your mollies fight the infection.
4. Medication: Use a commercially available Ich treatment medication. Follow the instructions carefully.
5. Clean the tank: Clean the tank thoroughly, including the substrate, decorations, and any equipment.
6. Isolate infected fish: If possible, isolate any infected fish in a separate quarantine tank to prevent further spread.
Important:
* Don't overcrowd your tank: 8 mollies may be too many for a 30-gallon tank.
* Maintain good water quality: Regular water changes and proper filtration are essential.
* Quarantine new fish: Always quarantine new fish for at least two weeks before introducing them to your main tank.
By following these steps, you can help your molly fish recover from Ich and prevent future infections.