Koi Skin Scapes: A How To Guide
If your koi are behaving oddly you’ll need to determine the reason for the strange conduct in order to resolve the issue that has occurred. First analyze pond water with a test kit to determine if all water parameters are within acceptable levels. Simple tests can rule out water quality as the trigger for unusual koi behavior and point you in a different direction. If water quality passes with flying colors then proceed to parasite activity as the next possible cause. Fish parasites are both microscopic and macroscopic. Skin scrapes must be performed to identify microscopic parasites as this type cannot be seen with the naked-eye. Fish parasites are usually discovered this way; the majority of harmful koi parasites are microscopic.
The purpose of taking a skin scrape is to obtain a sample of mucus from a koi’s cuticle, or slime coat, for analysis under a microscope. The mucus specimen is examined for significant parasitic existence. Remember that parasites are always present in low numbers but when a koi has been stressed parasites will flourish and can become problematic.
Typical behavior in koi suggesting skin scrapes be performed:
The purpose of taking a skin scrape is to obtain a sample of mucus from a koi’s cuticle, or slime coat, for analysis under a microscope. The mucus specimen is examined for significant parasitic existence. Remember that parasites are always present in low numbers but when a koi has been stressed parasites will flourish and can become problematic.
Typical behavior in koi suggesting skin scrapes be performed:
- Flashing and darting, or rubbing on pond edges, as if to rid an irritant.
- Loss of appetite.
- Hanging motionless in water.
- Unusual gill activity; clamped gills or excessive movement or panting.
- Clamped fins.
- Isolation, not mixing with other koi.
- Foggy eyes, patches of fungus, bumps, sores, ulcers or lesions.
- Congregating in high oxygen concentration areas such as waterfalls or around air stones.
- Lying on its side on pond bottom, exhibiting sharp movements if disturbed only to resume lying down position.
- Reddening of skin or fins.
Performing skins scrapes can be a daunting task. Getting good quality skin scrapes will take practice. Accurate parasite identification with a microscope will take even more practice. With time you’ll gain confidence in handling your koi and become proficient at obtaining and preparing specimens for microscopic examination, or biopsy.
Skin Scrapes
Things you will need to perform successful skin scrapes:
- Sock Net
- Koi viewing bowl
- Sterile glass slides
- Sterile plastic cover slips
- Microscope
- Pen & Paper
- One cup of pond water & eye-dropper
- Tweezers
- Hand towel
- A helper
Assemble all of the necessary equipment on a clean dry surface. Before you begin, decide how many scrapes you will be performing. Set out a clean piece of paper for every scrape, label and number each one with a corresponding scrape location; left flank, flank to tail, right gill, etc. These sheets of paper will keep your slides organized and provide a great place to jot down notes both before and during sample collection and examination.
Suggested koi skin scrape sites are as follows:
Suggested koi skin scrape sites are as follows:
- Flank: Along the Fish's side.
- Caudal: Base of the tail onto tail.
- Gill Operculum: External gill cover and on to the pectoral fin.
- Gill Filament: Tissue of the gill, under the gill cover.
- Chin: Cleft between gill covers underneath the fish.
- Wound of Ulcer: A sore or any spot that appears to be showing damage
Fill a koi viewing bowl with pond water just to a depth sufficient to cover the fish. Using a sock net carefully put one koi into the viewing bowl. You will hold the fish with one hand and perform the skin scrape with the other. Try not to touch the areas designed as scrape sites. Never blot, wipe or wrap the koi in a towel. This would remove the pests that you are trying to capture from the cuticle. If the koi is of substantial size a helper may be needed. When handling koi you should try to remain calm and maintain quiet surroundings. It is a good idea to give your koi a break and a chance to breathe in between each scrape. By releasing it momentarily you’ll ensure it gets through the ordeal with minimal stress.
Start by holding your fish against the side of the viewing bowl with its flank (side) out of the water. Grasp the slide firmly, hold at a 45 degree angle, press it down on the fish, apply some pressure and drag the edge of the slide along the flank from shoulder towards the tail. Never go against the scales as damage may occur. By applying slight pressure you should be able to scrape some mucus from the skin. You only need a small amount, about the size of a pencil eraser. The intended prize, mucus, will be clear or vaguely opaque. Once you have a sample on the slide place one drop of pond water on top of the mucus, and gently place a cover slip on top. The cover slip will force the mucus to spread out on the slide, perfect for viewing under a microscope. Place your prepared slide on the appropriately labeled paper and keep it out of direct sunlight. Move on to gather more samples.
For best results, your samples should be examined within 30-60 minutes of being collected. Tweezers will come in handy if any macroscopic parasites are discovered, such as anchor worm or fish lice.
Start by holding your fish against the side of the viewing bowl with its flank (side) out of the water. Grasp the slide firmly, hold at a 45 degree angle, press it down on the fish, apply some pressure and drag the edge of the slide along the flank from shoulder towards the tail. Never go against the scales as damage may occur. By applying slight pressure you should be able to scrape some mucus from the skin. You only need a small amount, about the size of a pencil eraser. The intended prize, mucus, will be clear or vaguely opaque. Once you have a sample on the slide place one drop of pond water on top of the mucus, and gently place a cover slip on top. The cover slip will force the mucus to spread out on the slide, perfect for viewing under a microscope. Place your prepared slide on the appropriately labeled paper and keep it out of direct sunlight. Move on to gather more samples.
For best results, your samples should be examined within 30-60 minutes of being collected. Tweezers will come in handy if any macroscopic parasites are discovered, such as anchor worm or fish lice.
Koi Gill Biopsy
Taking a sample from the gill of your koi is a little trickier. Fish really do not like to cooperate with whoever is lifting their gill plate cover (operculum) or sticking an object under it. You will most likely need a second set of hands to help when taking gill samples. Now is your chance to get a good look at the gills and visually inspect them for damage or signs of tissue malfunction. You should make note of anything unusual such as pale pink streaks or areas of discoloration within the normally crimson red gill tissue. White edges, frayed tips, holes, heavy mucus, or blood clots on the gill filaments are also reasons for concern. As well, build-up of scar tissue with a trunk-like appearance rather than individual delicate gill tissues is an indication of heavy parasite infestation. All of these conditions are evidence of gill damage from parasite activity or chemical burn.
Instead of obtaining a mucus sample with the edge of a glass slide, this time you will use a sterile plastic cover slip to retrieve the gill sample. Again, hold your fish against the side of the viewing bowl. Working quickly, lift the operculum and gently wipe the gill filament with a corner of the cover slip, then release the fish. This sample will look different than a body skin scrape. It will be pink or red and look like tissue rather than clear mucus. Don’t be alarmed if you get a little bit of blood with the sample or if the fish bleeds from the gill following the procedure. Place the coverslip, sample side down, on a clean glass slide. To stay organized, set the slide down on your previously numbered sheet of paper. Now you can study the scrapes under a microscope and review your notes, or continue taking more samples.
Instead of obtaining a mucus sample with the edge of a glass slide, this time you will use a sterile plastic cover slip to retrieve the gill sample. Again, hold your fish against the side of the viewing bowl. Working quickly, lift the operculum and gently wipe the gill filament with a corner of the cover slip, then release the fish. This sample will look different than a body skin scrape. It will be pink or red and look like tissue rather than clear mucus. Don’t be alarmed if you get a little bit of blood with the sample or if the fish bleeds from the gill following the procedure. Place the coverslip, sample side down, on a clean glass slide. To stay organized, set the slide down on your previously numbered sheet of paper. Now you can study the scrapes under a microscope and review your notes, or continue taking more samples.