1. Different types of air-breathing in fishes

2. Amphibious air breathers
Facultative air breathing
Aquatic air breathers
Obligate air breathing
Amphibious air breathers

3. Aquatic air breathers Facultative air breathing Obligate air breathing
Some aquatic air breathers only breathe air if they need to and can otherwise rely on their gills for oxygen.
Obligate air breathing
Other aquatic air breathers must have access to air or they will drown.
Although there are some temperate air-breathing fishes, most live in tropical habitats where high temperatures dramatically reduce dissolved oxygen levels in water. Many of these tropical air-breathing fishes live in freshwater habitats in which high rates of decomposition further decrease the amount of oxygen available and a thick forest canopy inhabits aquatic photosynthesis, which would add some oxygen to the water.

4. Hypostomus plecostomus African lungfish
Facultative air breathing
Obligate air breathing
Hypostomus plecostomus
African lungfish

5. Amphibious air breathers
Some fishes also have the ability to survive, and even remain active, while out of the water due to their ability to breathe air.
These include some tropical freshwater species in habitats that may become dry seasonally (providing additional selective pressure for aerial respiration) and marine intertidal species that leave the water to forage.
Mudskipper

6. Air-breathing organs
Those that are derived from the gut , such as the lung, gas bladder, stomach, or intestine.
Structures of the head and pharynx, such as modifications of the gill, mouth, pharynx, or opercles.
Skin, which can be very effective for gas exchange if it well vascularized and kept moist.

7. Difference Aquatic air breathers Amphibious air breathers
To aquatic air breathers, air breathing is a mechanism to survive low oxygen in the water.
To amphibious air breathers, air breathing provides a means to take advantage of a habitat not available to other fishes.

8. Thanks for your attention!