When the level of the ocean or another body of water reaches its highest elevation at a specific location during a specific period, it is referred to as a high tide. Low tide is opposed by it. The h…

A catadromous fish hatches and spawns in salt water but spends most of its life in fresh water.  Catadromous life cycles are much less common than  anadromous  life cycles.  American and European Ee…

M aximum sustainable yield (MSY) is a classic concept from fish population dynamics.  It operates under the assumption that populations have a carrying capacity, or equilibrium size, where the the resou…

Chondrichthyes are a taxonomic class of cartilaginous fishes that encompass sharks and rays ( elasmobranchs ) and chimaera.  Though there are exceptions, in general, Chondrichthyes have exposed gills…

Monogamy is a mating system where partners live and exclusively mate with only each other. These pair bonds can be transitory, just for a single breeding season, extend for several years or even a lifetime…

Polygyny is a polygamous mating system where a male has multiple female partners during the breeding season. This is the more common form of polygamy. Bluehead Wrasse form polygynous harems Polygynous males, like slimy sculpins ( Cott…

FISH MATING STRATEGIES In honor of Valentines Day, please enjoy the first series of post for this blog post on  fish mating strategies !   Check back weekly for new additions to the “Fish-ionary.” Promiscuous : A mating system where both sexes hav…

Promiscuous is a mating system where both sexes have multiple partners during the breeding system. In fishes, this is the most common mating system. Breeders make little or no mate choice and spawn with multiple partne…

Polygamous is a mating system in which an individual of one sex has multiple partners during the breeding system but individuals of the opposite sex have only one partner.  Evolutionarily, these systems are purport…

Polyandry is a polygamous mating system where a female has multiple male partners during the breeding season. This is a relatively uncommon form of polygamy and has only been reported in anemonefish ( Amphiprioninae ) …

Ichthyology is the study of fishes*.  With an estimated 27,977 species, fish are the most numerous and diverse group of vertebrate species.  In fact, there are more fish species than all other groups of vertebrates …

The anal fin is found on the ventral side of fish, often, but not always, at the base of the anus.  Along with the   dorsal fin , the main purpose of the anal fin is stabilize the fish and keep it from…

The pelvic fins are paired fins found on the ventral (bottom) side of fish.  In teleost (bony) fishes, pelvic fins placement gives some indication of evolution.  For more basal groups, the pelvic fins…

The pectoral fins are the two fins located on the sides of a fish (or marine mammal).  These fins are primarily responsible for control of directional movement, up and down or side to side.…

The dorsal fin is a stabilizer fin                            The dorsal fin is located on the top of a fish (as well as some marine mammals).  Predominately, the fin is used to stabilize fish in the water and help direct the fish through turns and …

The caudal fin, or tail, of a fish is the only fin to be connected to the vertebral column.  It is the primary means of locomotion for most fish.  Unlike many marine mammals with tails that use …

The adipose fin is a small fleshy fin found posterior to the dorsal fin and anterior of the caudal fin.  It is only found on few fish, including trout, salmon, and catfish.  When it was …

The pelagic zone is the region of a body of water (lake, river, or ocean) that is not associated with the bottom ( see benthic zone ) or shore ( see littoral zone ).  This habitat …

The benthic zone is region of a body of water (lake, river, or ocean) that is near the bottom.  It includes the surface and some of the sub-surface layers of the sediment.  The sediment can sand, mud…

The littoral zone is the region of a body of water (lake, river, or ocean) that is near the shore.  While there is no exact definition of the zone, in marine systems it is generally consi…

IUU fishing is   illegal ,   unregulated , and   unreported   fishing.  According to the   2001 FAO International Plan of Action to Prevent, Deter and Eliminate Illegal, Unreported, and Unregu…

Finlets are highly specialized fins located on the dorsal and ventral sides of the body between the  dorsal fin  and/or the  anal fin  and the  caudal fin .  They are only found on certain fish inc…

The length of a fish is often used for fish population assessments (e.g., length-age and weight-length relationships) and consequently are often used in recreational fishing regulations.  But, just as there is “…

Otoliths are ear bones in fish.  Bony fish (not sharks or rays) have three pairs of otoliths: Sagitta : detects sound and converts sound waves into electrical signals (i.e., hearing); Asteriscus : detects sound and is involved in hearing; a…

Cycloid scales are smooth-edged scales predominately found in lower order teleost fishes, such as salmon, carp and other soft fin rayed fish.  Similar to  ctenoid  scales, they are overlappin…

Ctenoid scales are scales with comb-like edge found in higher order teleost fishes, such as perch and sunfish.  Cteni are the tiny teeth on the posterior margin of the scale.  Similar to  cycloid  scal…