Ich & velvet treatments

Active ingredient: Kordon Rid-Ich Plus: formaldehyde 4.26% (11.52% formalin) + zinc-free malachite green chloride 0.038%. Seachem ParaGuard: proprietary aldehydes (10% by weight) + malachite green + fish-protective polymers; no formaldehyde or methanol. API Liquid Super Ick Cure: malachite green oxalate <0.1% (SDS; other identity/percentages withheld as trade secret); product page carries a Prop 65 warning for nitrofurazone

How to use (from the label): Product-specific. Rid-Ich Plus: 1 tsp (5 mL) per 10 US gal (15 mg/L formalin + 0.05 mg/L malachite green), 20-25% water change before each re-dose, repeat every 24 h (as often as 6-12 h) until 3 days after the last spots, carbon removed. ParaGuard: 5 mL per 40 L daily, chemical filtration removed, 14 days for ich, 14-21 days for velvet. API Super Ick Cure: 5 mL per 5 US gal, repeat after 48 h, then after another 48 h change 25% and add fresh carbon (not a daily dose).

Careful: Invertebrates (shrimp, snails, corals): remove them / do not treat a tank holding them - no manufacturer recommends a half dose for invertebrates. Scaleless and sensitive fish (loaches, eels, rays etc.): API says half dose; Seachem says start at 1/4-1/2 dose and build up; Kordon says Rid-Ich Plus may be used on scaleless fish. Formalin lowers dissolved oxygen: aerate. Do not combine Rid-Ich Plus with other medications. Human safety: formaldehyde is a known carcinogen; malachite green and nitrofurans have shown carcinogenic effects; avoid skin/eye contact.

Rules: Malachite green and nitrofurans are not FDA-approved for any food-producing (aquacultured) animal in the US and are treated as unsafe drugs/food additives in food fish. Formalin is FDA-approved for fish only as the products Parasite-S and Formacide-B. Seachem labels ParaGuard for ornamental fish only, not for animals used for human consumption.

Never mix medicines unless the label says it is safe, and remove shrimp and snails unless the label says they are safe.

Examples you may see in shops: Kordon Rid-Ich Plus, Seachem ParaGuard, API Liquid Super Ick Cure. Not endorsements. Always follow the label.