How many times a day do fish come up fir air?

Most fishes never come to the surface for air. Most 'breath' water, extracting oxygen from water they pump across their gills. Frequently fish in oxygen depleted water will rise to the surface and take in water from just below the surface because there is usually a higher concentration of oxygen there. Fish 'gasping' at the surface of an aquarium or pond usually indicates that the water quality has deteriorated.

There are some fishes with specialized gills that allow them to breath air directly, and obtain some of their oxygen in that manner. These fishes usually are found in water with normally low oxygen levels, as may be found in bogs and swamps. The ability to breath air directly sometimes diminishes the ability some species to obtain all of their oxygen from the water, so these fish usually need to visit the surface periodically each day.

There are also obligate air breathers who must obtain most of their oxygen from the air. Lungfish are an example. Mudskippers are another example of air-breathing fish. Such creatures are, however, unsuited for life on land, and must exist at least partially in the water. There is a great variety of adaptation and variety among fishes in breathing and related activities. Even air breathing fish must remain moist at all times. The ability of fishes to breath air and/or water covers a broad spectrum, generally dictated by environmental factors.