Freshwater fish ecosystems
Other than in aquaria and garden ponds, Britain's freshwater fishes have to be considered as integral elements of the ecosystems of which they are a part. This includes not merely the mix of omnivorous, predatory and other fish species, but the plants, invertebrates, birds, mammals, fungi, amphibians and reptiles with which they mesh as part of complex food webs. The British people have a well-known obsession with the weather, a constant feature, or at least a punctuation, of many conversations. Other freshwater fishes found occasionally in caves, more probably visiting than resident, include minnows and flounders, as well as European eels, Atlantic salmon and three-spined sticklebacks. Adequate extent and diversity of habitat in brackish waters is also crucial for species migrating between saline and fresh water, providing for their diverse needs as their physiology adjusts as they move between differing salinity regimes.