Fish Medicine Flashcards
1
Q
‘Pet’ fish temperate freshwater - Goldfish basic requirements (Teleosts)
A
- 30 L water per fish
- 1 ft^2 of air surface per fish, can be reduced by aeration (pump pushing air through water, will inc SA + reduce air at tank to maintain oxygenation)
- Maintain 18 - 20 C, warmish room temp
- Cope in open-air pond year-round
- Ponds preferable to tanks if deep enough to avoid freezing/shade available in summer
- Feed on crustaceans + plants or pelleted food (flakes)
2
Q
Koi karp
A
- Large ponds 1.5 m depth
- Filter w/ biological + physical filtration to accommodate their size + metabolism
- Multiple chambers in filter - filter out lumps of organic material -> sand type, takes out smaller particles -> biological filter - may be spoken w/ bacteria that break down protein by-products in water + remove, water flows back = relatively clean
- Aeration - waterfalls for larger systems
- Commercial diets - vit C, carotenoids to maintain bright colouration
3
Q
Common issues of carp
A
- Water quality failings, problems w/ protein breakdowns - inc NH3, nitrates or nitrites - should be removed by water changes/used by aquatic plants
- Any organic material in water produces NH3 + NH4+
- NH3 more toxic - causes damage to surface of fish + diffuses across gills
- Need idea of proportion of NH3 : NH4+
- Mod levels but have alkaline pH/high temps, get shift of NH4+ -> NH3, will higher NH3 than results suggest
- NH3/NH4+ oxidised by bacteria mostly in filtration system -> NO2- (nitrite) -> oxidised further to nitrate (NO3^2-), dec toxicity, tend to be sequestered in water + doesn’t go far, used by some aquatic plants + take it out the water
- Can have systems w/ de-nitrifying towers - remove nitrites
- Small amount removed as N2 gas
- To remove majority of nitrates, will have to do water changes
4
Q
Causes of spikes in NH3/nitrates/nitrites
A
- 1). Failure to prepare + mature a tank + filter - bacteria need to be implanted into system + build-up its numbers, prepare tank
- Filter before introduce fish using filtration material from another tank to populate the filter or commercial liquid populations to put on sponges -> run tank w/ organic material e.g. fish food and allow to stabilise for few w
- 2). Overstocking - can be gradual as fish grow/breed, may be too small filter
- When sudden inc in no. fish by new group + don’t allow filter to adapt
- 3). Failure of filter - stop water circulating, place AB -> kill all bacteria
- 4), Overload or organic material -> overfeeding, algal or plant bloom, dead fish
- Inc feed
- Algae die -> inc release of organic matter
5
Q
Consequences of spikes in NH3 (first stage)
A
- 1). Irritation of skin - discomfort, ulceration, inc risk of skin infection
- Become more active + twisting in water/rubbing against side of tank/pond
- Ammonia burns
- Abrasions - rubbing against things
- Skin infection - barrier of skin damaged + opportunistic bacteria can take advantage + cause ulceration + infection
- 2). Gill epithelial hyperplasia - 2y effects on oxygenation -> resp signs, reduced osmosis + NH3 excretion
- Thickened gills - don’t have effective diffusion - less O2 pass over -> hypoxia
- More vulnerable to hypoxic stress
- Resp signs
- Dec excretion of toxins
- 3). General debilitation due to chronic stress
6
Q
Consequences of spikes in nitrites (NO2-)
A
- Inc nitrite absorption
- Hb oxidised to methaemoglobin - doesn’t carry Hb as efficiently
- Hypoxia due to reduction in O2 transport
- Pale tan mucosa + gills
7
Q
Consequences of spikes in nitrates (NO2^3-)
A
- Rarely clinical in itself - not particularly toxic
- May affect eggs + fry - juveniles affected, may affect fertility + development of fry
- Facilitates algal + plant bloom, only produce O2 during the day - 2y drop in oxygenation - use up O2 overnight -> O2 crash = sudden die-off -> sudden release of organic material
8
Q
Water quality management
A
- Water changes - 30 - 50% of tank pond vol, don’t replace w/ normal tap water, chloramines will wipe out filter bacteria + toxic to fish, need sample of pre-prepared water, allowed to age + allows chlorine gas to diffuse out or Tx water w/ commercial products to remove chlorine + chloramine
- Add zeolite to bind NH3 + immediately removes from water, but cannot leave in place or NH3 released bak out into water, take out + place in salt water + reuse = temp sink for NH3
- Reduce organic load - remove algae + plants overgrowth, reduce feeding - can just stop feeding for few days
- Remove debris - siphoned out but be aware of dec water quality
- Improve oxygenation - aerate water, cool or shade water if hot weather - will hold more O2 at cooler temps - ice bottles or adding colder water
9
Q
Longer term water quality management
A
- Identify + manage cause
- If fish died = remove, simple matter
- Allow filter maturation - re-populate
- Inc filter capacity
- Reduce stocking of plants or fish
10
Q
Low O2 saturation
A
- 1). High biomatter load - algae, fish decomposing vegetation - plants overnight when CO2 production continues + no O2 produced
- 2). High temps - O2 saturation dec w/ inc temp
- Severe issues
11
Q
Low O2 saturation - CS + Dx
A
- 1). Die off - early morning when O2 lowest
- 2). Fish gathering at point of aeration - trying to suck in air at surface
- Failure of normal diffusion - gill damage, or not enough O2
- 3). Signs of chronic stress - ulcerative skin disease, mortality of already compromised fish
- Dx - measure O2 saturation at sunrise
- Lower mortality at milder stages - those already compromised e.g. tumours are the ones that die first but still down to O2
12
Q
Low O2 saturation - managment
A
- Remove biomass - stable oxygenation throughout day + night
- Inc aeration e.g. hose at height, fountains, waterfalls, commercial - depends on size of the enclosure, aeration stones in small tank
- Dec stocking density - relocate permanently/temporary removal until dealt w/ 1y issues
- Provide shade/cool water
- Monitor nitrogen processing - NH3 + nitrites also inc due to common factors
13
Q
Ulcerative skin disease - parasitic
A
- Common in koi
- Protozoa - Ichtypthirius multifillis (Ich) - small white spots + irritation of fish - rubbing + showing irregular movements
- Gyrodactylus skin flukes
- Dactylogyrus gill flukes
- Argulus lice
- Lernea anchor worm -> focal irritation
- Then can get 2y bacterial infection due to injury to skin
14
Q
Ulcerative skin disease - bacterial (1y infection)
A
- Aeromonas spp most common - diffuse reddening + 2 y ulceration when skin sloughs off
- Range of environmental bacteria can be opportunistic invaders - Pseudomonas - when got skin surface damage
- Primary bacterial infection rare - commonly 2y: trauma, damage to skin barrier e.g. high NH3
15
Q
Skin disease - viral
A
- Rarely ulcerative
- Cyrpinid herpes
- Can be ulcerative but typically presents w/ raised plaques
- Not great deal to Tx - will remain infected
- Will see viral flares - cold, dec immune system but low mortality
19
Q
Medication admin of fish medicine
A
- Orally - compound into pelleted or gel food (set in ice cube trays - indv Tx) - oxytetracycline for koi + pond fish
- Can create own mix
- Injections - epaxial muscles either side of dorsal fin, hard to restrain (stressful)
- In water - dissolve/dilute, bypass filtration system - remove bacteria/take fish out until cleared out bacteria, powder/liquid directly y in water then return to normal pond
- Short term dips of higher conc
- Temp affects dosing requirements + freq
20
Q
Swim bladder disorders
A
- Goldfish
- Altered buoyancy - suggestive, but can be due to GI disease (distension), neoplasia, granulomas (TB) or ascites (renal neoplasia)
- Stuck at top/bottom of tank, unable to feed well, bump into walls, abrasions around eyes
- 2y concerns - inability to feed, abrasions
- Infection/anatomical disruption alters swim bladder filling
- Dx - radiographs - highlight swim bladder alterations in position, size or shape
(Elasmobranchs + some bottom-dwelling teleosts e.g. flounders + some pelagic teleosts e.g. tuna lack a swim bladder) - Physoclistous species - marine teleosts, cichlids, bass + sunfish - gases diffuse into swim bladder from rete mirabile - bloodstream ‘gas glands’
- Physostomous species (koi + goldfish, catfish, salmon + trout, tetras) - pneumatic duct connects oesophagus + swim bladder, bacteria, fluid, FB or food can enter swim bladder = more swimbladder issues; koi have rete mirabile as well as duct
21
Q
Swim bladder disorder - Dx
A
- Radio/US to check for mass or fluid displacing the swim bladder - done consciously, cope for short periods w/o water, put in dish where cannot jump out in lateral
- Aspirate for culture + cytology -> AB
- US - when fluid/water gets in the way
- V fibrous tissue - hard to interpret mass unless well-defined
- Can instil sterile saline + aspirate back if appears to not have much fluid in swim bladder
26
Q
Tropical freshwater - common conditions
A
- Water quality issues - if have breakdown of aeration system can lead to O2 depletion but less common as less temp variation + less vegetation overgrowth
- Fin rot (similar pathology to ulcerative skin disease)
- Conspecific and intraspecific trauma - deplete numbers when grow in size
- Mycobacterium marinum - zoonotic, occasional issues
- Lymphocystis
- White spot (Ich)
- Fungal skin disease
- Velvet (Piscinoodinium)
- Hole in the head (Hexamita)
31
Q
Marine tropical - common diseases
A
- Water quality issues
- Cryptocaryon (similar to Ich protozoal)
- Marine velvet (Amyloodinium)
- Lymphocystis
