Water temperature decides how hard a fish will chase. Here is the curve for each species.
Fish are ectotherms, so in the model temperature is the master variable: it sets metabolism, and metabolism sets how far the fish strikes, how fast it can chase and how much it wants to eat. These are the six curves The Fish uses, shown in °F first.
All six curves
Horizontal: water temperature, °F above and °C below. Vertical: model metabolism. Dashed red line: 20%, where the model treats the fish as shut down.
- At 50 °F the rainbow trout model is the most active, at 63%, ahead of northern pike at 46%. Below the 20% cut-off: largemouth bass and bluegill.
- At 85 °F the largemouth bass model is the most active, at 82%; the rainbow trout model is at 2%.
- Peak window. The largemouth bass model keeps 80% or better across the widest span (75 °F to 85 °F); the rainbow trout model across the narrowest (53 °F to 63 °F).
Metabolism at fixed temperatures
| Species | Optimum | Feeds at all | 40 °F | 50 °F | 60 °F | 70 °F | 80 °F | 90 °F |
|---|---|---|---|---|---|---|---|---|
| Largemouth bass | 81 °F | 45–93 °F | 2% | 13% | 36% | 65% | 98% | 41% |
| Smallmouth bass | 70 °F | 41–84 °F | 2% | 26% | 60% | 100% | 45% | 2% |
| Walleye | 68 °F | 36–81 °F | 12% | 37% | 70% | 95% | 12% | 2% |
| Northern pike | 64 °F | 34–79 °F | 17% | 46% | 82% | 79% | 2% | 2% |
| Rainbow trout | 57 °F | 34–72 °F | 22% | 63% | 93% | 21% | 2% | 2% |
| Bluegill | 75 °F | 46–90 °F | 2% | 12% | 40% | 78% | 84% | 2% |
2% is the model's floor outside the feeding range, so a 2% cell means "not feeding", not "slightly active".
One page per species
What the curve is, and what it is not
Below the optimum, metabolism rises as a power of how far the water has warmed from the cold limit. Above it, it falls faster, reaching the floor at the warm limit. The optimum and the two limits are working assumptions for each species, not calibrated measurements, and the model has no seasonal acclimation, thermocline or spawning-temperature triggers. The mechanics are in How it works; the known errors are listed atwhere this model is wrong.
Related research
Cited from published studies. All guides →