Mosquito Fish Emergency: Bubbles = Low O₂, Algae Food Killed It

Class experiment, pregnant mosquito fish in tank with algae food → surface bubbles, foggy water. Algae food decayed → methane → O₂ crash.

Immediate Rescue

1. Move fish to clean, aerated water NOW.
2. Remove algae food — source of decay.
3. Snail dead (scrunched, immobile) — same cause.

Follow-Up: Black Spot

• Fish tail black on one side = **black spot disease** (fluke cysts).
• Cycle: bird feces → snail → fish → bird.
• Cure: Remove snails, deter birds.

Tank Hygiene

• No algae food blocks.
• Small water changes daily.
• Sponge filter + air stone.

Algae food = poison. Clean water = life. Black spot = remove snails.