How to collect blood from the tail vein of a fish.

Collecting fish blood for testing can generate information on the health of the animals including states of inflammation (e.g. bacterial infection), viral infection, their immunocompetence and more.

Collecting blood from a fish can be likened to collecting it from the tail vein of cattle. I’ve uploaded a video (http://youtu.be/MPoqU6721_Q) demonstrating with an anaesthetised koi fish. In dorsolaterally compressed fishes, and if the needle is not of sufficient length, the needle may be inserted diagonally. Landmarks: midline, spinal column & level with the lateral line.

For reasons why we collect blood in fishes, check out more information on my blog – https://thefishvet.com/?s=haematologyImage

Sexing koi

To follow on from my previous post, text books will often tell you that a male koi will be slimmer and have a longer head. Female kois will have a wider, deeper body and a shorter, more feminine head.

Those in the know will also add that during the breeding season, the male fish will be rougher to touch along their flanks and over their operculae (gill covers). The females on the other hand, will have smoother skins.

Your female kois will be roeing up now in preparation for spawning which would occur over the next few months. You might notice males showing more interest in the females and will chase them when they are ready to spawn.

Sexing fish

Sexing fishes are one of the most common things people ask fish keepers. Many would want to purchase a male and a female fish.

So, how do you tell the difference between a male and a female fish? In general, male fishes tend to have longer or more elaborate finnage and more intense colouration. Females tend to be bigger and more rotund in order to carry their eggs. Some species such as the live-bearing guppies, mollies, platies and half-beaks have their anal fins modified from the fan shapes (seen in females) to elongate tubes known as a gonopodium. Sharks and rays have similar long appendages known as claspers.

Evaluation of three types of … floating plastic media … biofilters …

Aquacultural Engineering
  Volume 45, Number 2 (September 2011)
Evaluation of three types of structured floating plastic media in moving bed biofilters for total ammonia nitrogen removal in a low salinity hatchery recirculating aquaculture system
   Authors: Timothy J. Pfeiffer 1, Paul S. Wills 2
   Author Affiliations:
 1: USDA Agricultural Research Service, Sustainable Marine Aquaculture Systems, 5600 U.S. Hwy 1 North, Fort Pierce, FL 34946, USA
 2: Harbor Branch Oceanographic Institute at Florida Atlantic University, Center for Aquaculture and Stock Enhancement, 5600 U.S. Hwy 1 North, Fort Pierce, FL 34946, USA
   Source: Aquacultural EngineeringVolume 45, Number 2 (September 2011)
   Page Numbers: 51 – 59
   Available Full Text:
Full Text: Subscription Required to view full text
Format: PDF
Size: Unknown
Location: Publisher’s Site
Authentication: Publisher’s Site
   Abstract: Three different types of floating plastic media were evaluated for ammonia nitrogen removal in 0.11m3moving bed biofilters of a low salinity warm water recirculating aquaculture system. The three types of media evaluated were K1 kaldnes media, MB3 media, and AMB media. The highest volumetric total ammonia removal rates (VTR) was observed with the MB3 for the two daily feed load rates evaluated, 3.5 and 8.3kgfeed/m3media. The VTR for the respective feed load rates were 92.2 and 186.4g TAN removed/m3media-d. The percent removal was also highest for the MB3 media, 12.3 and 14.4% for the low and high feed rates respectively.
   Citation: Timothy J. Pfeiffer, Paul S. Wills . Evaluation of three types of structured floating plastic media in moving bed biofilters for total ammonia nitrogen removal in a low salinity hatchery recirculating aquaculture system. Aquacultural Engineering, Volume 45, Number 2 (September 2011), pp. 51-59, <http://ejournals.ebsco.com/direct.asp?ArticleID=46BEB7ACF158628A2E4B>
   URL: http://ejournals.ebsco.com/direct.asp?ArticleID=46BEB7ACF158628A2E4B

How long can fish stay out of the water?

Of course my answer will begin with…. It depends…on the fish, the environment (temperature and humidity).

In warm tropical countries, it is not unusual to find some fishes such as catfish, snake heads and eels to cut across land to get where they’re going. They could be out for many minutes if the conditions are right.

Are your pond fish safe from predators?

Cormorants, pelicans, herons, cats and more can inflict serious damage to your prized pets or eat them.

What are some signs that make you suspect such is the case?

  1. Certain fish are missing (usually the smaller ones).
  2. Fish are injured on the dorsum (over their back or dorsal fin).
  3. Fish are not coming up to eat or are very skittish.
  4. Fish jump out.
What are some things you can do to remedy the situation?
  1. Put a cover/barrier over the pond (e.g. netting, fishing line, plank).
  2. Use “scare crows” (e.g. T-shirts on hangers, crocodile ornaments floating in the water, a sticker of a shadow of a bird of prey on a window).
  3. Use “scare birds” (herons are territorial, so a plastic model of one may deter other herons – but make sure you move the model bird daily so that other birds will not realise that it’s a fake!).
  4. Use “biological scare tactics” – have more human activity near the area or employ a jack russel dog!
  5. Colour your pond green! Research shows that birds fly over many water bodies and the colour of the pond determines whether the bird would come closer for a look. Green ponds are often avoided because the birds believe that there is likely to be an algal bloom and fishing in such a pond would be a waste of their time.
  6. Provide hiding spots for your fish so that they can avoid predation – have these in deep parts of the pond.
If you have any more tips, please do not hesitate to add to these.
Fish = Good.
Bird = Bad.

Now on: Twitter – Blog – Facebook – Linkedin – Flickr

Yours sincerely,

Dr Richmond Loh
BSc BVMS MPhil (Vet Path) MACVSc (Aquatics & Pathobiology) DipPM CMAVA

Veterinarian / Adjunct Lecturer Murdoch University
The Fish Vet, Perth, Western Australia. Mobile Veterinary Service for fish and other aquatic creatures.
http://www.thefishvet.com.au
Ph: +61 (0)421 822 383

How accurate is your water test kit?

Have you been monitoring your water quality? Water quality is one of the most common causes of fish ailments.

In the last 2 weeks, I’ve had 2 cases where the clients’ water test kits were inaccurate. Please check that your water test is current. Generally speaking, most test kits have a shelf life of 1-2 years (depending on storage conditions, the test, brand and physical properties [powder vs tablets vs liquid]).

If your test kit is >2 years old, then it’s time to invest in a new set. When purchasing a new test kit from the aquarium store, you can choose your test kit using one of two methods. The first method is by looking at the price – usually, the higher quality, more reliable kits will be more expensive (you get what you pay for). The second method I will outline is because quite often, the manufacturers do not print their date of manufacture or used by dates. So, ask the retailer whichis the most popular brand that they sell. This method of buying means that the stock is turned over more quickly and so you can be more certain that you’re getting “fresh” kits – not the ones that have been sitting on the shelves for a long time, gathering dust.

Until next time… Happy fish keeping!


Now on: Twitter – Blog – Facebook – Linkedin – Flickr

Yours sincerely,

Dr Richmond Loh
BSc BVMS MPhil (Vet Path) MACVSc (Aquatics & Pathobiology) DipPM CMAVA

Veterinarian / Adjunct Lecturer Murdoch University
The Fish Vet, Perth, Western Australia. Mobile Veterinary Service for fish and other aquatic creatures.
http://www.thefishvet.com.au
Ph: +61 (0)421 822 383

 

How to do a fish autopsy?

Sometimes, it is not always possible to make a diagnosis clinically and so, lab testing may be required.

To do this, fish will need to be freshly dead and the necropsy video I have placed on youtube will help you perform the necropsy.

http://www.youtube.com/watch?v=gZ8HWUEQL5c&feature

The fixative I use is 10% neutral buffered formalin. If you are unable to obtain this, then less suitable alternatives include:

  • formalin you use to treat fishes diluted 1:10 (i.e. 10% formalin solution),
  • methylated spirits diluted 7:10 with water (i.e. 70% methanol solution),
  • or household vinegar used neat.

The volume of fish tissues to fixative should be 1:10 for best results (but 1:5 is also acceptable). When sampling larger fish specimens, tissue sizes should be >1cm thick. Gills and intestines are the first to decompose and so these tissues need to be preserved in the fixative as soon as possible.

NB: Formalin is considered to be carcinogenic. Do not inhale or contact formalin. Wear suitable personal protective equipment.