Fish

What is the most common fish used in research?

Zebrafish

What types of studies are zebrafish used in?

• Developmental biology

• Carcinogenicity assays

• Aquatic toxicology

Why are zebrafish used in developmental biology studies?

Embryos are clear → can test drugs to see if they impact in-utero development

What two fish are primarily involved in aquatic toxicology studies?

• Fathead minnow

• Medaka

What type of research are goldfish used in?

Neuroscience

What four fish are primarily involved in aquaculture?

Channel catfish, rainbow trout, Atlantic salmon, tilapia

Which type of fish is highly resilient and can grow in diverse conditions?

Tilapia

Gills are both a __________ and __________ organ.

Respiratory; excretory

Fish excrete ammonia through _______.

Gills

What is the primary excretory organ of the fish?

Kidney

The kidney of a freshwater fish __________ salts and ___________ water.

Conserves; excretes

The kidney of a saltwater fish __________ salts and ___________ water.

Excretes; conserves

Since fish do not have bone marrow, what organ produces blood cells (hematopoiesis)?

Kidneys

What fish species demonstrate nephron neogenesis?

Goldfish, tilapia, rainbow trout

The swim bladder is an outpouching of the ______________.

Digestive tract

What are the functions of the swim bladder?

• Maintains equilibrium

• Respiration

• Sound production

• Perception of pressure fluctuations

The swim bladder communicates with which organ in some species?

Esophagus

How can you release pressure from an overfilled swim bladder?

Burping fish

What is the lateral line?

Sensory hairs located along sides of fish

What is the function of the lateral line?

Detect vibrations in water → help fish navigate dark/murky water

How many chambers does the fish heart have?

Two → atrium and ventricle

What do catfish have all over their bodies, especially on the barbels?

Taste buds

What three things do fish lack?

• Lymph nodes

• Bone marrow

• Parathyroid gland/hypercalcemic organ

Where are phagocytic cells present in fish?

Endothelium of atrium and gill lamellae

Where is calcitonin produced in fish?

Ultimobranchial body

What organ do zebrafish lack?

Stomach

In addition to the kidney, where are blood cells produced in the fish?

Spleen and mesentery

What fish organ produces urotensins that assist with osmoregulation?

Urophysis

Look at the fish fins

I have looked

Which fin is removed in farm-raised fish?

Adipose fin

What are the two types of fish tanks in relation to filtration?

Static and recirculating

What do mechanical, chemical, and biological filtration remove from water?

• Mechanical: particulate matter

• Chemical: free ions

• Biological: nitrogenous waste products

What three things must be present in rooms housing fish tanks?

• Floors that can hold heavy equipment

• Floor drains

• GFI outlets

What is important about the water temperature when housing fish?

Minimal temperature fluctuation

What fish are cold water species?

Trout, salmon

What fish are warm water species?

Zebrafish

Describe the nitrogen cycle.

Uneaten food and fish waste → ammonia → nitrite → nitrate → plant material

What do Nitrosomonas bacteria oxidize?

Ammonia to nitrite

What do Nitrobacter bacteria oxidize?

Nitrite to nitrate

When does new tank syndrome occur?

Introducing fish into unconditioned water

What is new tank syndrome?

Ammonia concentrations rise rapidly without Nitrosomonas and Nitrobacter bacteria to break down ammonia

What are three ways to prevent new tank syndrome?

• Seed new tank with bacteria from working aquarium

• Gradually add new fish to a tank

• Feed fish sparingly for 3-4 days

What is the recommended pH in fish tanks?

6.7-7.0

What are things you have to monitor regarding the water quality of fish tanks?

• Oxygen, carbon dioxide

• Ammonia (nitrates, nitrites)

• Chlorine, chloramine

• pH

• Hardness (CaCO₃)

• Contaminants → heavy metals, soaps, disinfectants

What two metals can leach into water from metal pipes?

Zn, Cu

Fish generally need high _________ in their diets.

Protein

Why shouldn’t you overfeed fish?

Leftovers foul the water

What do you feed zebrafish?

Brine shrimp eggs

Where can you collect blood from a fish?

Caudal vein

What is the most common substance used to anesthetize a fish?

MS-222 (tricaine methane sulfonate)

What are the considerations you must make when anesthetizing a fish?

• Powdered form of MS-222 is health hazard

• Buffer with NaHCO₃

• Keep skin moist

What is an experimental fish anesthetic that is potentially carcinogenic but has no withdrawal time?

Aqui-S (isoeugenol)

What are the considerations you must make when performing surgery on a fish?

• Use sterile gloves and instruments

• No shaving

• No skin prep/disinfectants → disrupts slime layer, skin infections

• Keep skin moist

How can you euthanize a fish?

• Anesthetic overdose

• Rapid cooling for zebrafish

What fish disease causes raised white nodules in the skin?

Ick/Ich/White spot disease

What causes white spot disease?

Protozoan

Which bacteria causes fish granuloma in people?

Mycobacterium marinum

How can people get fish granuloma? How can you prevent it?

Gets into people through breaks in the skin → wear gloves when handling water from aquariums

Which company provides diagnostic health monitoring for zebrafish?

Inotiv