Why Shrimp Die From Products That Don't Bother Fish

Shrimp physiology is the issue

Shrimp (and most invertebrates) use copper-based hemocyanin rather than iron-based hemoglobin for oxygen transport — which means even trace copper levels that are harmless to fish directly disrupt their respiratory chemistry. Concentrations measured in single-digit parts per billion can be lethal to sensitive shrimp species.

Common, easy-to-miss copper sources

• Tap water run through old copper plumbing, especially in older buildings
• Fertilizers and plant supplements — some contain trace copper as a micronutrient for plants
• Medications — many fish "ich" and parasite treatments are explicitly copper-based and will wipe out a shrimp colony even at labeled fish-safe doses
• Algae control products containing copper-based algaecides

Practical precautions

Test your source water for copper if you're keeping sensitive shrimp (Caridina species especially — Neocaridina tend to be hardier). Read medication labels specifically for copper sulfate or chelated copper before treating any tank housing shrimp, and when in doubt, quarantine sick fish elsewhere rather than treating the shared display.