Hand Creams, Lotions, Soap and Cosmetics When Working in the Tank

Whatever is on your hands enters the water: soap, lotion, sanitiser, sunscreen, perfume and DEET all harm fish and inverts. The rule: rinse hands and arms with plain water only.

Every time you put a hand into the aquarium, whatever is on your skin can dissolve into the water. Hands and forearms routinely carry substances that are harmless to us but dangerous to fish and, above all, to invertebrates. This is one of the most common and most preventable causes of a sudden, unexplained tank wipe-out.

The culprits

• Soap and hand sanitiser residue: aquaria have been wiped out by people who still had soap on their skin after doing the dishes
• Hand lotion, moisturiser and sunscreen: oils and UV filters such as oxybenzone are toxic to shrimp and fish
• Perfume, cologne and makeup: fragrances and solvents dissolve into the water
• Insect repellent (DEET): toxic to freshwater fish and zooplankton
• Nicotine from a smoker's hands

Why it matters

Surfactants in soap, oils in lotion, alcohols in sanitiser, and fragrances and repellents like DEET all dissolve or disperse into the water, where they can irritate gills and harm sensitive animals. Shrimp and other invertebrates are especially vulnerable, because the same chemistry that makes a product cling to and condition human skin makes it harmful in the closed volume of a tank.

The rule

1. Before working in the tank, rinse your hands and forearms with plain water only, with no soap.
2. Remove hand lotion, sanitiser, sunscreen and similar products from your skin first.
3. For sensitive shrimp or reef tanks, or if you have anything on your skin you cannot remove, use aquarium-dedicated nitrile gloves, rinsed in plain water before use.
4. Save soap and sanitiser for after you have finished, and wash between tanks to avoid cross-contamination.