AQUA ME Terminologies: Fish

AGNATHA/ JAWLESS FISH

• Body is covered in skin, with no scales

• Skin has copious slime glands, the slime constituting their defense mechanism

Cyclostomes

round mouths

Anadromous

migrating up rivers from the sea to spawn

CHONDRICHTHYES/ CARTILAGENOUS FISH

• Sharks, Skates, and Rays

• Cartilaginous skeletons

• Denticles

• Mostly has 5-7 gill slits (depending on species)

• No swim bladder

Squalene

CHONDRICHTHYES have oil rich liver called

oviparous

egg-laying

ovoviviparous

egg laying but incubates the eggs inside their body

OSTEICHTHYES/ BONY FISH

• Over 20,000 species worldwide (most fishes)

• Skeletons are calcified, making them much harder than the cartilage bones of the chondrichthyes

• Equipped with swim bladder to control buoyancy

CYCLOID SCALES

Type of Scales that have a smooth texture and are uniform

CTENOID SCALES

Type of Scales that like cycloid scales, with small teeth along their outer edges.

GANOID SCALES

Type of Scales that are usually thick and do not overlap

PLACOID SCALES

Type of Scales that found in the cartilaginous fishes: sharks, rays. 

• They are also called dermal denticles.

Chormatophores

Pigmented Cells, responsible for camouflaging

LATERAL LINE

• These lines are composed of neuromasts (tiny sensory cells) which contain cilia in fluid filled canals. 

• These canals detect vibrations in the water 

• the vibrations form an image inside the fish’s brain

Single loop system

Oxygen deprived blood comes from the body tissues → and organs → and goes to the heart → then pump to the gills to gather oxygen → then goes to the circulation again to distribute oxygen

Closed Circulatory system

Blood remains only in the blood vessels and does not fill body cavities

Osmoregulation

• Maintaining proper salt balance 

• freshwater fish need salt and therefore must excrete water in order to maintain internal homeostasis

Spawning

• Mature fish releases gametes (ova and sperm) ; 

• fertilization of eggs is performed Externally

Milt

Sperm from the male fish

Egg scattering

• Female releases eggs in the water  w/o any specific protection 

• ex : Salmon and Herrin

Mouth Brooding

• One parent, often the female carries the fertilized eggs in their mouth until they hatch. 

• Ex: Cichlids, some catfish sp. Arowana

Nest Building

• Fish Construct nest using different material like plants or any substrate they can find. 

• This practice is commonly seen in fresh-water species. 

• Ex : Puffer Fish

Bubble Nesting

• Fish build a clump of bubbles by taking air and blowing it out, creating a protective environment for the eggs 

• Ex : Betta Fis

Swim Bladder/ Air Bladder

• A gas filled bag that sits in a fish’s body cavity above its gut

• A fish with swim bladder can control its depth by regulating the amount of gas in the bladder

Physostomous Swim bladder

• some fishes remove gases from the swim bladder by expelling them through a special duct that attaches the swim bladder to the esophagus. 

• The swim bladder of modern fish is an Ellipsoidal, Gas-filled sac that arises as an extension of the gut.

Physoclitous Swim Bladder

In Fishes that do not possess pneumatic duct, their swim bladder empty when gasses diffuse back into the blood.

Farming

implies some form of intervention in the rearing process to enhance production, 

• such as regular stocking, feeding, protection from predators, etc.

• also implies individual or corporate ownership of the stock being cultivated.

External protists (or ectoparasitic protists)

are single-celled eukaryotic organisms that live on the outer surfaces, skin, gills, or shells of a host organism rather than invading its internal organs or bloodstream

Ciliates

• have short, fine cytoplasmic outgrowths called cilia as the locomotory organelle. 

• They are either attached or motile. 

• are a group of complex, single-celled microscopic organisms (protists) defined by hair-like structures called cilia. 

Sessile

means attached directly by the base without a stalk, stem, or petiole, or permanently fixed to a surface without the ability to move around

Flagellate

• have one or more long, hair-like structures called flagella used as a locomotory organelle. 

• They occur on the skin, gills, intestinal organs, and blood of fish.

• have one or more long, hairlike structures called flagella used as a locomotory organelle. 

• They occur on the skin, gills, intestinal organs, and blood of fish

Oomycetes

• Although they (water molds) share some morphological traits with the true fungi, they are more closely related to diatoms, opalinids, and labyrinthulomycetes. 

• These primarily saprophytic organisms are common to freshwater fish around the world.

Monogenean Parasites

Flatworms, external flukes

• highly pathogenic, and obligate parasites most commonly seen on skin and gills. 

• The preferential location of some species is in internal organs such as the esophagus, stomach, posterior kidney, or urinary bladder.

Cestodes

Tapeworms

• uncommon in cultured fish complex life cycle that requires one or two intermediate hosts fish can be an intermediate host, definitive host, or both

bothria

• are elongate, shallow, dorsal or ventral longitudinal grooves or slit-like pits 

• located on the scolex (head) of certain cestodes, such as Diphyllobothrium or members of the order Bothriocephalidea. 

• They act as weakly muscular attachment organs that pinch or grip the host's intestinal mucosa. 

Contracaecum Infestation

Contracaecum spp.

Acanthocephaliasis/ Thorny Headed Worm Infestation

Acanthocephala spp.

Spiny Proboscis

Acanthocephala They feature a retractile, hook- or spinearmed head that they use to drill into and anchor themselves firmly to the fish's intestinal wall 

Crustacean infestations

parasites have segmented bodies covered by shell with jointed appendages

Hirudinids

Marine leeches

• are segmented worms that attach to the skin, finds, gills, and eyes of marine and estuarine fish to feed on their blood.

Guppy killer

Often referred to in the aquarium hobby as the cause of "guppy killer disease" due to rapid, high-mortality outbreaks

Adhesive Disc

Spinning motion of this organ can cause direct damage to the epithelium of fish

Ambiphrya

 they have a cylindrical shape with a distinct row of oral cilia and a middle band or equatorial girdle of cilia used for movement before attachment

Apiosoma

 Vase- or bell-shaped single-celled organisms visible under a microscope.

Epistylis

a stalked, colonial protozoan parasite that attaches to a fish's skin, fins, or eyes, feeding on bacteria and organic debris in the water

Piping

laying over then dash their sides against the objects

Flashing

Rubbing of their body against the surfaces

tomont stage

 is the adult stage of the parasite. When this adult tomont leaves the fish, it falls to the bottom of the pond  

haptor

identified by their characteristic holdfast organ which is armed with large and small hooks 

Opisthaptor

attachment organ at the rear part that hooks and anchors to the fish’s skin and fins