Week 13 Exotics

Fish that eat other fish

Piscivorous

What is important in hematopoiesis in fish?

Kidney (they don’t got bone marrow)

Air filled sac that allows fish to control buoyancy

Swim bladder (they can control the amount of air in there to go up or down)

Bony fish

Teleosts

Cartilaginous fish

Elasmobranch

What the difference in water through gills in teleosts vs elasmobranch fish

teleosts- pump water through mouth and operculum to gills

elasmobranch- move through water to drive in water over gills 

How do elasmobranchs keep buoyant

Store lipid in liver and light cartilaginous skeleton (NOOO swim bladder)

What is the major hematopoietic tissue of elasmobranchs

Epigonal organ

In elasmobranchs what is secreted in the rectal glands and why

Excess salt to maintain osmoregulation of the blood in saltwater environment

What part of the gill is involved in gas exchange in the gills of teleosts and elasmobranchs

Gill lamellae 

It involves releasing food on the surface of the water. It allows all fish, including shy or slow eaters, to access food. Common in community tanks and ponds, this technique helps reduce competition and ensures fair feeding distribution.

Broadcast feeding

In this feeding method individual animals are offered food directly—either by hand in shallow systems or using a feeding stick or tongs in deeper systems. This technique allows for precise monitoring of food intake and individual animal health.

Hand or stick feeding

It refers to the use of positive reinforcement techniques to train animals to approach a specific location or object in order to receive food. This method enhances animal husbandry by facilitating health checks, behavioral enrichment, and stress reduction during handling

Target feeding

It involves delivering food to aquatic animals while submerged, typically during scuba diving. This method may include feeding multiple individuals from a bucket or offering food by hand or with specialized tools. It is commonly conducted during public presentations in large-scale aquarium exhibits to combine animal care with educational outreach.

Underwater feeding

A container, typically made of glass or acrylic, used to keep and display live fish and other aquatic animals. It can be transparent or opaque depending on the purpose of use. They come in different capacities but usually 20–55-gallon aquarium is preferred for display at home.

Aquarium/tank

Enhance oxygenation by producing small bubbles that agitate the water surface, increasing gas exchange through diffusion which is vital for fish health. Low dissolved oxygen levels cause hypoxia, leading fish to gasp at the surface. Conversely, excess dissolved gases may result in gas bubble disease, where bubbles form in fish blood and tissues. Air pumps also power air-driven devices like sponge filters and bubble walls, promote water circulation, and add to the visual appeal of the tank.

Air pump

Cleans and maintains water quality in an aquarium. Different fish species require different water conditions, and the filtration system plays a key role in maintaining these conditions. Mechanical filtration removes debris and keeps water clear, biological filtration breaks down toxic waste via beneficial bacteria, and chemical filtration eliminates dissolved impurities and keep water healthy for aquatic life.

Filter system

Used for monitoring aquarium water quality

Test kits

In saltwater tanks this contains beneficial bacteria that aid in biological filtration

Live rock

Provide hiding spots, reduce fish stress, and mimic natural habitats

Ornaments

What does a sick fish look like?

• Anorexic

• Lethargy or Weakness

• Loss of buoyancy control

• Erratic swimming

• Schooling fish may separate from the group

• Increased or decreased opercular movements

• Flashing or shimmying (to be continued…)

• Lesions

What are the major components to the skin of fish

Epithelium, scales, goblet cells

Why is the skin especially important for innate immunity in fish

They are in direct contact with their environment

What is the purpose of scales for fish

Protection, reduce water drag, camouflage

What are lamellae covered by

Single layer epithelium and endothelium (thin for gas exchange)

What structure in the gills gives rise to lamellae

Filaments

Which pneumocytes do fish have

One type of cell (thought to be a mixed of type 1 and 2)

What increases contact time between water and blood in gills and is very important for osmoregulation and ammonia excretion

Countercurrent exchange

What pulls water into the mouth in teleosts

Buccaneers pump

What pump flows water over the gills and out in teleosts

Opercular pump

What structure results in water flow over the gills and out the gill slits in elasmobranchs

Buccaneers pump

What is another term for gillitis

Branchitis

What is a unique place you find goblet cells in fish which can lead to catarrahal exudate there

Skin

What does every physical exam in fish include

Skin scrape and gill clip wet mouth cytology

What body system is usually involved in surface breathing (dyspnea) in fish

Gills (respiratory)

What leads to diffusely pale and swollen gills in fish

Epithelial hyperplasia

What is true about the heart in fish

Single circuit of arterial and venous flow with a 2 chambered heart

What is the blood flow through the heart in fish based on the structures it goes through

Sinus venosus → atrium → ventricle → bulbus arteriosus

What separates the heart from the coelmic cavity

Transverse septum

How can the caudal vein of fish be accessed

Lateral- Insert needle in lateral line caudal to anal fin using vertebrae as landmark

Ventral- Insert needle caudal to anal fin using vertebrae as landmark

In which fish will you use cardiac puncture and why

Stingrays and skates (have more superficial heart)

What are lymphatic vessels referred to as in fish and what are characteristics of it

Secondary circulatory system (NO lymph nodes, vessel anastomose between veins, more volume than primary, maybe osmoregulation properties)

Decreased function of the bulbus arteriosus will most likely result in what physiologic effect on the fish?

Irregular systolic blood pressure

Which fish have a higher solute component in their body when compared to the environment and what will this cause

Freshwater (water will be pulled in)

Which fish have a lower solute component in their body when compared to the environment and what will this cause

Saltwater (water will be pulled out)

What substances are high in elasmobranchs and what is the purpose of this

Urea and TMAO which makes them have a higher solute conc inside compared to the saltwater environment

Do freshwater fish drink more or pee more

Drink less and pee more (saltwater drink more and pee less)

A freshwater fish has a systemic bacterial infection with severe inflammation and necrosis of the kidney. What type of fluid issue may this patient present with clinically?

Ascites (coelomic cavity fluid)

Dropsy (fluid build-up in cavities and tissues)

(Because they pee more and can’t pee it all out)

A saltwater grouper from a public aquarium has a similar bacterial infection in the kidney. What sort of fluid imbalance might you see as a sequela and how could you treat the fluid issue?

Dehydration (give fluids)

In teleosts which part of the kidney is more hematopoietic and which is involved in osmoregulation and excretion

Hematopoietic- Cranial kidney

Osmoregulation- Cadual kidney

What does the whole kidney function as in elasmobranchs

Osmoregulation

They glomeruli of freshwater teleosts and elasmobranchs is what compared to saltwater

More functional (need to pee a lot)

What are the main hematopoietic organs in teleosts and elasmobranchs?

Teleosts- Head kidney, spleen

Elasmobranchs- Epigonal organ, spleen

What do RBCs look like in fish

nucleated

What do fish have instead of platelets

Thrombocytes

What granulocytes are seen in fish which have less impact on inflammation than in mammals

Neutrophils, eosinophilia granulocytes (main granulocytes in fish), basophils (stingrays)

What is the main response to injury and infection in fish

Granulomatous (macrophages)

Why is creatinine lower in freshwater fish

They pee a lot

What must be diluted for analysis in sharks and why

BUN (because they have a lot of urea so it seems like a lot)

Swim bladder connects to esophagus through pneumatic duct (e.g. trout, carp, catfish, and others)

Physostomous

Swim bladder connects to vascular rete and gas gland (e.g. goldfish, koi, perch, and others)

Physoclistous

What composes the swim bladder and what is the function

collagen, elastin, and lined with thin sheets of guanine crystals

(makes it impermeable to gas)

What does the liver look like in an anorexic shark

Small (can lead to problems with buoyancy)

What does the liver look like in teleosts

Some lipid accumulation but not as much as elasmobranchs

Which type of fish have a longer intestinal tract

omnivorous/herbivorous

What is blind ended and increases surface area in the GI tract of some fish

Pyloric cecae

What does the brain process a lot of in fish

Visual processing

Fish have nociceptors but don’t have what

Neocortex

Which fish should you be careful about using NSAIDs in

Saltwater (bc its processed through the kidney and they don’t pee a lot)

What is a sensory organ in fish that detects water movement, vibration, and pressure gradients And is also useful landmark for venipuncture

Lateral line

Benzocaine derivative absorbed through gills and skin and blocks Na gated action in sensory and motor nerves

Tricaine methanesulfonate (MS-222, Tricaine)

Does distended body cavity mean over conditioned

NO not all the time (ex ascites)

What are different devices used to test water quality

Colorimetric, titration kit, probes, photometers

What does poikilothermic nature mean

temperature drives metabolism and homeostasis

Is temperature drop or rise more tolerated in fish

Drop

What happens to fish at decreased temperature

Metabolic rate, growth rate, and immune system slow down

What happens to fish when water temperature increases

Increased metabolic rate puts stress on organs and cells and ability of Na/Cl ATPase enzymes to function, including those involved in osmoregulation, more likely to see mortality

What range of O2 do fish need

6.5 - 8 mg/L or 80 - 120 % saturation

Does warm water hold more or less oxygen

Less (an fish will require more metabolically)

Too high total dissolved gas pressure in the water relative to the atmosphere (especially nitrogen)

Supersaturation (gas bubble dz)

What are some causes of supersaturation

○ Cold water (deep well or spring) will hold more gas until it comes to surface and warms and gas is released

○ Phytoplankton blooms coupled with warming water late in day

○ A cracked pipe, waterfall by a dam, etc. will suck more atmospheric gas in the water

What happens to a fish with gas bubble dz

Nitrogen absorbed through gills into blood stream → Gas is released but trapped within tissues → Gas emboli form in bloodstream and emphysema in the tissues

Nitrogen is metabolized to what and excreted into the water

Ammonia

What are the different types of filter used for fish and what do they filter (which needs to be cleaned)

Mechanical- particles from water (fabric, charcoal, mesh)…need to be cleaned

Bio filters- remove nitrogen water (ammonium and nitrate)….never clean

What is the teamwork system that converts ammonia eventually to nitrate (least toxic form)

Ammonia -nitrosomonas spp. bacteria→ Nitrite -Nitrobacter spp. bacteria→ nitrate

Where does bacteria come from in aquariums

Biofilms (dont clean this up its good)

Ammonia up…..

Fish down

What is ammonia toxicity

New tank syndrome

What is nitrite toxicity

Brown blood dz

What is nitrate toxicity

Old tank syndrome

What causes new tank syndrome

Too many fish added before biofilm has grown , overcrowding, tanks cleaned or antibiotics kill biofilm

What do water quality kits measure in terms of ammonia

TAN (total ammonia)- ionized and unionized

What causes brown blood dz

Nitrobacter spp. growth lags behind Nitrosomonas spp. (“bro stop”)

Methemoglobin lacks ability to release O2 leading to hypoxia

What causes old tank syndrome

Increased carbon dioxide can result in what pH of water

Acidic (decreased CO2 would lead to basic)

What are the reference ranges for the pH in freshwater vs saltwater fish

Freshwater- 6.5-8

Saltwater- 7.8-8.4

What can cause acidosis in closed indoor systems

Metabolic activity can reduce pH, bicarbonate used up

What can cause acidosis in closed outdoor systems

CO2 high in mornings due to photosynthesis, ground water, soil, acid rain

What are the different salinity amounts for saltwater bs freshwater systems

Saltwater- 30 ppt

Freshwater- 0.5 ppt

What causes water hardness

Buildup of magnesium, calcium and salt (leads to osmotic stress in fish)