Zebrafish Health & Husbandry: ILAR Journal 2012 Flashcards
Which of the following fields of research was the first one to expand when using zebrafish models as part of an integrative approach to improve human health:
a. Toxicology
b. Aging
c. Oncology
d. Developmental genetics
d. Developmental genetics
Which of the following agents is the most common cause of Microsporidiosis in laboratory zebrafish:
a. Pseudoloma neurophilia
b. Pseudocapillaria tomentosa
c. Schistocephalus solidus
d. Pleistophora hyphessobryconis
a. Pseudoloma neurophilia
Which of the following Mycobacteria has been found to cause severe outbreaks of Mycobacteriosis in laboratory zebrafish:
a. M. fortuitum
b. M. chelonae
c. M. haemophilium
d. M. ulcerans
c. M. haemophilium
Which of the following wild-type strains was the one used for the sequencing and mapping of the zebrafish genome:
a. AB
b. SAT
c. TL
d. SJA
b. SAT
Name the two most common infections found in zebrafish submitted to the ZIRC diagnostic laboratory
Pseudoloma neurophilia (74%)
Mycobacterium spp. (43%)
Which species of mycobacteria is of particular concern because it infects humans?
a. M. fortuitum
b. M. haemophilum
c. M. chelonae
d. M. marinum
d. M. marinum
True or False: Acid fast staining is the primary technique recommended by the Zebrafish International Resource Center for routine surveillance.
True
True or False: The ability of piscine mycobacteria to persist in surface biofilms is not one of the challenges in eliminating infection.
False
Mycobacterium are facultative pathogens that can survive outside the host on biofilms. Screening animals & eggs alone may be ineffective at elimnating the infection.
Which of the following is the currently recommended treatment for elimination of mycobacteria from a facility once it has been established?
a. Vaccination with extracellular mycobacterial products
b. Depopulation
c. Vaccination with attenuated mycobacteria
d. Rifampicin
b.Depopulation
T/F: Mycobacteriosis in fishes is attributable to 3 species of mycobacteria: M. chelonae, M. fortuitum, & M. marinum
False: using more refined diagnostic methods, at least 16 mycobacterium species have been in fish
In zebrafish, at least 6 have been described
Which of the following are clinical signs of mycobacteriosis in zebrafish?
- Non-specific dermal lesions
- Raised scales
- Swollen abdomen
- Emaciation
- No clinical signs
- Erratic swimming
Clinical signs of mycobacteriosis are broad ranging, so any of the listed clinical signs are possible
ID male and female zebrafish
The male is smaller & more stream-liined
The female is larger with a distented abdomen
T/F: Mycobacteria have been observed in the ovaries of zebrafish, suggesting the potential for contamination of off-spring, if not vertical transmission
True
What is considered to be the primary route of transmission of mycobacteria in fish?
Ingestion: the intestine is likely the primary route of invasion
This highlights the importance of removing dead and moribund fish as soon as possible
Which of the following species of mycobacterium is of particular concern regarding zoonotic disease.
- M. chelonae
- M. fortuitum
- M. marinum
- M. haemophilum
M. marinum
It is known to infect humans
Direct transmission from fish has not been confirmed, but is strongly suspected
What is thought to limit the establishment and spread of fish-associated mycobacterial infections in humans?
Human core body temperature
Fish-associated mycobacteria do not grow well at 37ºC
Name two acid fast stains that can be used to ID mycobacteria in histologic sections.
Ziehl-Neelsen
Fite’s
Describe culture conditions used for mycobacteria
Middlebrook 7H10 agar supplemented with oleic acid, albumin, dextrose & catalase
Or growth on Lowenstein-Jensen Slants
Cultures are incubated at 28-30ºC and monitored for 6-8 weeks
Which of the following is considered the gold-standard for a thorough investigation and subsequent storage and cataloguing of mycobacterial species and strains?
- Acid fast staining of histo sections
- PCR detection & sequencing
- Culture
Culture
PCR detection & sequencing are useful to ID mycobacterial species, but not strains
T/F: Different strains of a given species of mycobacterium will develop their own unique properties & challenges.
True
Which of the following mycobacteria are associated with low-level chronic disease? Which are associated with higher virulence, disseminated infections, & higher levels of mortality?
- M. marinum
- M. chelonae
- M. abscessus
- M. fortuitum
- M. haemophilum
- M. peregrinum
M. marinum & M. haemophilum are associated with a higher level of virulence, disseminated infections & higher mortality rates
The others are associated with low-level chronic disease
T/F: Environmental conditions & the nutritional and immunological state of zebrafish are probably the most important variables affecting the pathogenesis of mycobacteriosis.
True
While different species & strains of mycobacterium have different effects, the overall health of the zebrafish affects the course of disease the most
T/F: All lines of zebrafish appear equally susceptible to mycobacterial infection
False
Different lines of zebrafish appear to be more or less susceptible to infection based on a cross-sectional study at a single facility (2 references listed)
Name the three tissues most likely to harbor mycobacterial granulomas in zebrafish.
Liver, kidney, spleen
T/F: In the aquatic environment, biofilms are found on all surfaces, and this biofilm and the detritus at the bottom of the tank are thought to be the source of mycobacterial infection.
True
T/F: The efficacy of the standard practice of bleaching eggs for 10 minutes at 50ppm is well established.
False
Various studies have evaluated the efficacy of bleach solutions on mycobacterial cultures exist, but no evidence regarding the efficacy of bleach myocbacteria in biofilms or on eggs exists.
Bacteria harbored within eggs are protected from disinfectants & present a risk to other eggs
T/F: The life cycle of Microsporidia consists of two general developmental stages: merogony and sporogony
True
Meronts multiply within the infected host cell, eventually forming sporonts and then spores, which are ultimately released from the host cell and transmit the infection.
T/F: Microsporidia are generally susceptible to many standard forms of surface decontamination used for fish eggs, such as chlorine and iodophores.
False.
The infectious spore stage has a thick, chitinous endospore making it extremely resistant to environmental stress and lysis.
T/F: Spores of P. neurophilia relesed from aggregates in myocytes or peripheral nerves in the somatic muscle typically elicit a severe inflammatory reaction.
True
T/F: Spores of P. hyphessobryconis can also be observed in the kidney, spleen, intestine and ovaries in heavier infections.
True
T/F: PCR-based assays are recommended for the specific detection of P. hyphessobryconis.
False.
No PCR-based assays currently exist for the specific detection of this parasite
T/F: the cryopreservation of zebrafish sperm prevents the spread of microsporidians.
False.
Microsporidians have the ability to survive during cryopreservation.
T/F: Pseudoloma neurophilia is the most common pathogen detected in zebrafish
True
Detected in 74% of the facilities examined by the ZIRC diagnostic service in 2010
What does ZIRC stand for?
- Zebrafish International Research Consortium
- Zebrafish Institute Research Center
- Zebrafish International Resource Center
- Zebrafish International Research Consortium
Zebrafish International Resource Center
Which of the following are clinical signs of Pseudoloma neurophila infection in zebrafish?
- Emaciation
- Lordosis
- Scoliosis
- No clinical signs
- Reduced fecundity
Infection produces a wide range of clinical signs & any of the listed signs are possible
Which of the following is a muscle-infecting microsporidium that has been described in laboratory populations of zebrafish?
- Paracheirodon innesi
- Pleistophora hyphessobryconis
- Danio nigrofasciatus
- Encephalitozoon cuniculi
Pleistophora hyphessobryconis
The following histology was obtained from a fish with emaciation and scoliosis…what is the diagnosis?
Pseudoloma neurophilia - microsporidiosis
A. Low magnification showing inflammation in skeletal muscle. Bar = 100 µm. Inset at upper left shows macrophage with 4 spores
B-D. Spores (arrows) in eggs. B) H&E. C) Acid fast, spores fill a degenerate egg, D) Gram, showing blue-staining spores.
E. Spores in spinal cord stain blue with the tissue Gram stain.
T/F: Microsporidian spores can often be seen in wet mounts from infected tissues and are discernible by their generally refractile appearance and characteristic posterior vacuole.
True
This is a wet-mount and geimsa stained tissue prepared from the brain & spinal cord of a zebrafish at necropsy. What is the diagnosis?
Microsporidiosis - Pseudoloma neurophilia
Pseudoloma from brain.
A. Giemsa stain
B. Wet mount with Nomarski’s phase interference
Bar = 10 µm.
What additional stain requiring fluorescence microscopy can be used to increase sensitivity of microsporidian spore detection by histology. An image below represents this stain.
Chitin-specific Fungi-Fluor stain
A. Low magnification showing numerous spores (stained blue with DAPI filter) in spinal cord xenomas (arrow).
B. High magnification of spores (S) in ovaries.
In which of the following tissues may large aggregates of P. neurophilia spores be seen?
- Neural tissue of the posterior brain & spinal cord
- Kidney
- Skeletal muscle
- Gut epithelium
- Ovary
Large aggregates are typically found in neural tissue of the posterior brain & spnal cord
Smaller groups or individual spores can be seen in the other tissues listed
What molecular diagnostic techiques are available for detecting P. neurophilia?
Convential & real-time PCR targeting the small subunit of the ribosomal DNA gene are available
T/F: Microsporidia are spread through direct transmission through ingestion of spores and infected tissue in the water
True
T/F: Zebrafish frequently spawn spontaneously in aquaria, and hence release of eggs, ovarian fluids, and tissues at spawning provides an important potential route of horizontal transmission.
True
T/F: Maternal transmission has not been reported for microsporidans in fish
False
Vertical transmission of microsporidans have been documented in fish
Experimental & observational lines of evidence suggest that maternal transmission of P. neurophilia, either transovarial or transova, does occur
Which of the following is considered the best method for routine health monitoring of zebrafish?
- Serologic testing
- PCR
- Culture
- Histopath
Histopathologic analysis is the best overall method for routine health monitoring of zebrafish because of the ability to assess all tissues and to detect novel pathogens, which would not be detected by PCR. Serologic testing is not available for zebrafish.
T/F: Exposing a population of known uninfected fish to the untreated effluent from other tanks on the system allows facility managers to assess the infection status of fish in the system on a large scale
True
Also…exposing sentinels to treated effluent can be used to assess the decontamination efficacy of the system.
What is the recommended quarantine procedure for introducing new fish into a facility?
Bring adults into quarantine, spawn them, and then move only the progeny of those adults that are screened and determined to be microsporidian-free into the main facility.
Which of the following doses of UV sterilization has been shown to be effective in the inactivation of microsporidian parasites of human concern?
- 1 mJ/cm sq
- 6 mJ/cm sq
- 30 mJ/cm sq
- 100 mJ/cm sq
6 mJ/cm sq
What is the generally recommended method of disinfecting zebrafish eggs with bleach?
Is this effective at killing P. neurophilia?
Bath treatment with 25-50 ppm bleach for 10 minutes
No, it is not effective at killing P. neurophilia & probably not mycobacterium
T/F: Microsporidian spores are highly resistant to current methods of surface sterilization of eggs, and these methods cannot be relied upon to eliminate P. neurophilia or other microsporidia from a population
True
T/F: Current molecular diagnostic methods can easily be applied to the testing of eggs, sperm, and larval fish. These methods have been used to establish P. neurophilia SPF colonies of zebrafish
True
What level of chlorine is required to kill >95% of P. neurophilia spores?
- 5 ppm, pH 7
- 5 ppm, pH 8
- 100 ppm, pH 7
- 100 ppm, pH 8
100 ppm, pH 8
Efficacy of chlorine is pH dependent
This dose is lethal for embryos
T/F: There are currently no known treatments for microsporidosis in zebrafish
True
Elimination by rederivation from uninfected adults is likely necessary for P. neurophilia
List some reasons why zebrafish have emerged as leading model for mechanistic cancer research.
Sophisticated genetic and genomic resources
Tractability for tissue-specific transgene expression
Cost effectiveness for enhancer and suppressor screens once a cancer model is established
T/F: Unlike other species, dietary and husbandry practices do not have a significant impact on the incidence of tumor development in zebrafish
False - diet and husbandry do affect the incidence and histologic spectrum of neoplasia in zebrafish
T/F: When compared to zebrafish raised in flow-through systems, zebrafish fed commercial diets containing fish meal and reared in certain recirculating water systems showed far higher tumor incidences and a much wider variety of histological types of neoplasia.
True
Recirculating systems & fish-meal diets are associated with a signifcantly higher incidence of neoplasia
What is the most commonly found mycobacterial species of fish?
M. chelonae
Where are Myxidium species found in infected fish?
Mesonephric ducts - invariably confined to the lumen or attached to the surface of epithelial cells & not associated with significant histopathologic changes
Name the capillarid nematode that is found in the proximal intestinal tract of zebrafish
Pseudocapillaria tomentosa
T/F: Fish affected with Pseudocapillaria are often clinically symptomatic & emaciated due to profound wasting.
True
This is a gut section from a zebrafish with severe wasting. What is the diagnosis?
Pseudocapillaria tomentosa
Histological sections of zebrafish with Pseudocapillaria tomentosa infections. Diffuse, severe chronic inflammation, extending from lamina propria (LP) into to visceral cavity.
Pa = inflammation in pancreas.
Arrow = nematode. Hematoxylin and eosin.
Bar = 100 µm
Name the condition in zebrafish that may be caused by egg retention in fish that have not had the opportunity to spawn frequently
Egg-Associated Inflammation & Fibroplasia (EAIF)
The condition is often subclinical, but affected females may have a swollen abdomen
How might EAIF confound toxicology studies?
Interpretation of endocrine disrupting compound studies might be confounded by spontaneous occurrence of chronic oophoritis, the hallmark of EAIF
What is the significance of hepatic megalocytosis in zebrafish?
Megalocytosis is characterized by hepatocytes that have both enlarged nuclei and excessive amounts of cytoplasm.
Hepatic megalocytosis can be caused by both natural toxins (cyanobacteria, alkaloids from plants) or a variety of anthropogeneic agents (recirculating systems with fluidized sand sanitizers, carcinogens)
T/F: Bile duct proliferation in the liver is often noted in normal appearing fish and seems to be particularly common in some lines of TL zebrafish.
True
Can confound studies looking at hepatic carcinogens b/c the appearance may be similar to neoplasia
Which of the following two neoplasms are commonly observed in histological examinations of apparently healthy sentinel fish?
- Hemangiosarcoma
- Ultimobrachial gland tumors
- Spindle cell sarcomas
- Intestinal carcinoma
Ultimobrachial gland tumors & Intestinal carcinoma
The others are not reported in zebrafish
Other spontaneous tumors in zebrafish include:
seminomas
malignant peripheral nerve sheath tumors
hepatocellular carcinomas
T/F: Zebrafish are not capable of contracting viral infections
False.
Zebrafish have been repeatedly infected experimentally with a variety of viruses.
What viral family is infectious spleen and kidney necrosis virus found in? Is this a DNA or RNA virus?
- Herpesviridae
- Paramyxoviridae
- Iridoviridae
- Reoviridae
- Birnaviridae
Iridoviridae
DNA
What is the genus and species of the Atlantic salmon?
Salmo salar
How many immunoglobulin classes does the zebrafish exhibit?
Three: IgD, IgM, and IgZ
T/F: The zebrafish genome is devoid of retroviral elements and transposons.
False
The zebrafish genome contains multiple endogenous retroviruses, retrotransposons, and other retroid agents.
What do we care if zebrafish have underlying viral infections?
- Regardless of whether clinical signs are evident, underlying infection with an unknown viral agent may confound experimental infection studies with a different pathogen.
- Viral infections may confound toxicologic studies or other studies that rely on histopathology by introducing unexplained histopathologic changes.
- Underlying infections may alter immune function
- Increased inflammation and altered cytokine production caused by underlying infections can affect cell proliferation rates, creating a confounding variable in tumorigenesis models.
- Zebrafish may be hosts to unknown oncogenic viruses, which may be a confounding variable in cancer research.
Why is biosecurity important for laboratory zebrafish?
Ornamental zebrafish are often raised together with other species that harbor numerous pathogens. A recent example of pathogen transmission from the pet trade to laboratory zebrafish is neon tetra disease, caused by the microsporidian Pleistrophora hyphessobryconis.
T/F: Zebrafish exhibit both the innate and adaptive arms of the immune system
True
With respect to the zebrafish immune system, which of the following is false?
- Leukocyte populations including B & T lymphocytes, monocytes, & phagocytic tissue macrophages
- Inflammatory mediators & signaling molecules
- Both Rag1 & Rag2 genes have been identified
- Both T-cell receptor genes & B-cell immunoglobulin genes exhibit V(D)J recombination
- 24 putative toll-like receptor variants have been identified in zebrafish
None - all of these describe the zebrafish immune system
Define “nutrition”
process by which living organisms acquire and assimilate nutrients for survival, growth, reproduction, and replacement of tissues.
What are two major limitations in the field of zebrafish nutrition?
A standard diet has not been established
The daily dietary nutrient requirements for any life stages are unknown.
Zebrafishes are:
a) eurythermal or b) sternothermic
Prefer a) areas of hydrodynamic activity or b) still water
Tolerate a) low ionic content or b) high ionic content
a) eurythermal: able to tolerate a wide range of temps (6-38℃)
b) still water
a) low ionic content (but not RO or distilled water)
What are the three general life support systems used to support zebrafish?
- Static renewal system
- Recirculating system
- Flow-through system
T/F: The mechanism of sex determination in zebrafish is not known
True
Zebrafish have no apparent heteromorphic (sex) chromosomes
T/F: It has been observed that sex ratios in propagated colonies are often variable, depending on rearing density, hypoxia, or food availability
True
Environmental factors, in addition to genetics, play a role in sex determination
T/F: In zebrafish, gonad development for both females and males is preceeded by a juvenile ovary stage
True
The juvenile ovary undergoes apoptosis and is restructured into a testis in males
T/F: Zebrafish are oviparous organisms with external fertilization and no parent care
True
Olfactory cues or pheromones have been show to play a role in which of the following?
- Synchronize mating behavior
- Increased egg production in females exposed to male pheromones
- Inhibition of spawning in females
- Mediate kin recognition
All are correct
T/F: As schooling fish, zebrafish do not form social hierarchies with dominant and subordinant individuals
False
Zebrafish do form social hierarchies which are important in breeding
Describe the three general phases of zebrafish courtship behavior.
- Initiatory stage: males follow or swim alongside females and exhibit abrupt swimming movements
- Receptive/Appetive stage: males touch the female’s side or tail with their noses or heads; females may remain still during this courtship
- Spawning stage: male and female swim side by side in the same direction and position their genital pores close to one another; male performs rapid tail oscillations against the female’s side, triggering oviposition and release of sperm
At what age to laboratory zebrafish attain sexual maturity?
3 months
T/F: Zebrafish mating is initiated by the onset light and spawning typically takes place over a short period thereafter
True
T/F: Because zebrafish are group spawners, group crosses/matings are used exclusively in the laboratory. Single-pair matings simply do not result in viable off-spring.
False
both single-pair matings and group crosses are used in the laboratory
What is the purpose of the perforations in the bottom of this tank?
Allows the fertilized eggs protection after spawning…the eggs pass throught he perforations protecting them from predation
What are some potential uses of single-pair matings in zebrafish?
ID carriers of recessive mutations
ID carriers of dominant traits visualized only during development - carriers must be ID by examining the progeny
TU, AB, WIK, and Tupfel ling fin are examples of what type of zebrafish line?
- Inbred
- Transgenic
- Wild-type
- Knock-out
Wild-type
What type of line is TAB?
Hybrid line between TU and AB
T/F: There are currently no zebrafish inbred lines in which all individuals are identical and homozygous
True
Inbreeding significantly reduces fertility and survivability in zebrafish
Describe 2 different types of tank designs for mating cross setups?
Mating crosses can be set up:
- In a static water tank over marbles
- In a container with a perforated bottom holding the fish. This container is located inside another container thereby protecting the eggs.
At what day post fertilization is the yolk completely absorbed which leaves the zebrafish larvae dependent on exogenous feeding?
a. 3
b. 7
c. 10
d. 15
b. 7
What is the preferred pH range of housing water for zebrafish?
a. 6.4-6.8
b. 6.8-7.2
c. 7.2-7.6
d. None of the above
b. 6.8-7.2
What is the standard rearing temperature for zebrafish?
What effect does temperature have on development?
28.5℃
Lower rearing temperature slows development while higher temperature accelerates it.
T/F: Feeding zebrafish Paramecium alone during the early larval stages can result in smaller larvae and lower survival rates, suggesting that Paramecium alone may be insufficient for nutrition
True
Paramecium-only diets are not adequate for proper growth and good survival rates. Although brine shrimp (Artemia) are not natural food items for zebrafish, they appear to fulfill needs for proper development.
At what age do zebrafish show decreased fertility, fecundity, and health.
Zebrafish older than 18 months show decreased fertility, fecundity, and health.
Which of the items listed below is not a common type of filtration in aquatic systems:
a. Biological Filtration
b. Chemical Filtration
c. Mechanical Filtration
d. Parasitic Filtration
d. Parasitic Filtration
T/F: The key advantage to UV sterilization is that there is very little maintenance needed once the system is established.
False
UV sterilizers need regular maintenance to perform adequately.
T/F: Most supplies of water from municipal sources contain chemicals toxic to fishes and must be pre-treated before addition to the system.
True
Most water supplies contain chlorine, chloramines, and possible leached heavy metals.
T/F: It is critical to keep all bacteria to a minimum in recirculating aquatic systems and regular addition of antibiotics is helpful.
False
Recirculating systems are critically dependent on bacteria in the biofilter to breakdown nitrogenous wastes.
Which modality of water quality testing and monitoring is preferred?
a. Automated monitoring
b. Manual monitoring
c. A combination of automated and manual testing
c. A combination of automated and manual testing
Name important factors with regard to water quality for the maintenance of zebrafish.
Temperature
pH
Salinity
Alkalinity
Hardness
Dissolved Oxygen
Nitrogenous Wastes
What is the target range for total ammonia nitrogen (mg/L) in zebrafish water?
- Zero
- 10
- 100
- Up to 200
Zero
What is the target range for nitrite (mg/L) in zebrafish water?
- Zero
- 10
- 100
- Up to 200
Zero
What is the target range for nitrate (mg/L) in zebrafish water?
- Zero
- 10
- 100
- Up to 200
Up to 200
Describe how reverse osmosis water filters work
- RO water filters are actually several individual water filters placed in series - each filter is referred to as a “stage”
- 1st stage removes sediment - particulate filter
- 2nd stage removes chlorine - activated carbon filter
- The water is then pushed through the RO membrane against its natural osmotic flow
- The water can then be de-ionized if needed
T/F: RO/deionized water must be conditioned with sea salts before being delivered to a life support system
True
This adds critical minerals
Describe how a flow-though life support system works
- What is the general water flow?
- What is the direction of water flow?
- Continuous or periodic?
- Water source consideration…..
- Clean water is pumped into tanks, fish excrete wastes, and the effluent is flushed out
- Flow is unidirectional - clean water in, effluent water out
- May be continuous or periodic
- Requires a large source of conditioned water
Describe how a recirculating life support system works.
- Describe the basic water flow
- How are wastes removed?
- Comment on water consumption
- Clean water is pumped into tanks, fish excrete wastes, effluent is pumped into “treatment zone” where wastes are removed before water is returned to the system
- Water recirculates in the system after filtration to remove wastes
- Greatly REDUCES water consumption
Why is it critical that solid wastes be removed from a life support system?
Solid wastes are produced by the accumulation of uneaten food and fish feces and have a detrimental effect on the efficiency of biological filtration
- Reduces available oxygen for biological filter
- Increases production of ammonia nitrogen
- Favors growth of heterotrophic bacteria that compete with bacteria of biological filter
Which is the function of Nitrosomas spp. in the biological filter?
Oxidize ammonia in the water to nitrite
Which is the function of Nitrobacter & Nitrospira spp. in the biological filter?
Oxidize nitrites to nitrates
What are the three factors all biological filters must maximize to function appropriately?
- Surface area of the media
- Water contact
- Oxygenation
Trickling media, moving bed bioreactors, and fluidized bed are all types of what kind of filter?
- Solids filter
- Biological filter
- Chemical filter
Biological filters
What is the function of chemical filtration in a zebrafish life support system?
Give some examples of chemical filters…
Removal of organic compounds, such as ammonia, not removed in solid and biological filtration that contribute to color and odors in effluent water. Will also remove chlorine which can come from municipal water supplies.
Activated carbon filter, ion exchange resins, ammonia binders
What is the recommended level of dissolved oxygen (mg/L) in aquaculture systems?
- 1
- 2
- 3
- >4
>4 or as close to saturation as possible
What is the recommended level of dissolved carbon dioxide (mg/L) in aquaculture systems?
- <20
- 20-40
- 40-60
- >60
<20 mg/L
What is the most frequently applied water disinfection method in zebrafish housing systems?
Ultraviolet disinfection
Name an advantage of using UV disinfection in aquaculture systems.
Relatively safe to operate
Not harmful to the cultured species
Why must bases be added to the water of life support systems?
Nitrifying bacteria of the biofilter continually produce acids, which if left unbuffered would eventually acidify the water to the point where nitrification would not occur. This can lead to ammonia spikes that can stress, injure or kill the fish
What is the purpose of a fluidized argonite reactor in a life support system?
It is an alternative to the standard sodium bicarbonate dosing method of maintaining pH
Aragonite is a form of calcium carbonate that, when in contact with water with pH <8, dissolves into calcium (adds to hardness of water) and carbonate (helps maintain pH)
T/F: Low levels of dissolved oxygen are responsible for more mortalities than any other parameter in aquaculture.
True - although this is rarely a limiting factor in zebrafish systems.
Leaching of what compound from older polycarbonate and polysulfone tanks can lead to serious reproductive problems in vertebrates, including fish?
Bisphenol-A (BPA): an estrogen mimic
What is an considered an acceptable stocking density for adult zebrafish?
- 1-5/L
- 5-10/L
- 10-15/L
- 15-20/L
5-10/L
The stress response in fish can be generally categorized into how many physiological stages? Name the stages.
Three – primary, secondary, and tertiary
What is the only anesthetic approved for some aquatic species by the US Food and Drug Administration?
MS-222 (tricaine methanesulfonate)
True or False: Under normal conditions, zebrafish are obligatory gill breathers.
True
How many levels of anesthesia are there in zebrafish?
Six (6) – levels 1-5 and stage 6
What organ is the most common target organ for nearly all carcinogens studied in WT & mutant lines of zebrafish?
Liver
Compared to mammals, zebrafish and trout more often show mixed hepatic neoplasms with biliary and hepatic components
