Freshwater and Marine Fish Do Not Share One Model

Fish are not one forecast category.

Freshwater and marine systems behave differently. Species behave differently. A pike in a summer lake, a zander on a turbid river edge, a seabass in tidal current, and a mackerel chasing bait in open water should not be pushed through the same generic model.

Gilli separates these worlds because the water does.

Freshwater Is Often Layered

Lakes can stratify.

Temperature bands, oxygen gradients, inflows, weed growth, clarity, and basin shape all shape fish location. A lake can change dramatically between spring turnover, summer stratification, autumn mixing, and winter conditions.

Depth matters, but only through usable water.

Marine Systems Move

The sea adds tide, current, salinity, coastal exposure, surf, and migration.

For marine species, movement can be tied to tidal flow, bait movement, seasonal arrival, water temperature, salinity tolerance, and structure. A stage label like "high tide" is often less useful than understanding current regime and local exposure.

The model needs that motion.

Shared Drivers Still Differ

Temperature, oxygen, light, season, and clarity matter in both systems.

But the way they matter changes. Salinity is central for many marine species and mostly neutral in freshwater. Tide can dominate some marine sessions and not exist on inland lakes. Thermocline can dominate a lake and be irrelevant at a shallow surf beach.

The factor name may be the same — the effect rarely is.

Species Profiles Are the Bridge

Species-specific profiles let Gilli interpret signals differently.

Preferred depth, thermal range, oxygen minimum, activity rhythm, clarity preference, pressure sensitivity, lunar sensitivity, habitat, and seasonal presence all help the app avoid one-size-fits-all advice.

Those profiles need evidence and provenance.

Otherwise the model becomes confident guesswork.

Better Questions

The old fishing app question is "is today good?"

The better question is: good for which species, in which water body, under which constraints, at which depth, and with what confidence?