How To Buy Healthy Fish And Avoid Sick Ones

This article pertains MOSTLY to koi and pond fish. But most of the recommendations hold for goldfish and tropicals as well. How To Buy Healthy Fish And Avoid Sick Ones

First, you should look for active, interested fish. The water in the holding tank should be rolling around and the water’s surface should be active. This is optimal for gas exchange and results in healthier livestock. The fish should be cruising below the water’s surface and chasing each other around. Don’t buy fish which are lethargically hovering in the water.

The fish should have a torpedo shaped body and by all means the fish should be “fat-looking”. Maybe you don’t know what “fat-looking” means. This means the abdomen or midsection should be as wide as the head. There should be a smooth contour from the head through the gills and into the body. If the belly of the fish is “pinched” you should not buy the fish. Lame excuses like: “They have been fasted and haven’t resumed eating yet” may be offered as an explanation. The smarter move should be to ask that the retailer should give you a call when the fish are eating again, and ready for sale.

The fish should eat when fed. If they don’t eat, don’t buy them. If the retailer offers the lame excuse that they were just fed, plan a return trip later to see if their appetite has returned. In case you didn’t know, healthy Koi in good water will always eat until they look a little bit like a fat ol’ tadpole.

Any disease or disorder you might note with one fish will also be carried by all the others in the group.

Look at the fish you want to buy for signs of “too much” slime occurring in patches on the body, or damage to the fins which would cause them to look like they were eaten away. Of great importance is also to notice the fishes’ nose, which should NOT have a red mark on it. It commonly occurs in retail tanks that the fish will “snub” their noses on the sides of the tanks. Unless you want a “project” with the strong potential for failure you should not buy infected fish such as those described in this paragraph. Again, you can tell the retailer in good faith that you are interested in a particular fish but you won’t assume the liability until the fish is “whole” again. I mean really, if the fish “is just fine” as so many retailers are quick to assure you, what’s the problem with waiting a few days for it’s lesions to disappear before closing the sale?

Any disease or disorder you might note with one fish will also be carried by all the others in the group. I made this mistake all the time when I was a kid. I’d see some gorgeous fish and fall completely in love with it. But there’d be this other fish in the tank with it that had a rotten mouth or a torn fin. So I’d rationalize that the fish I wanted to buy is “fine” and had no symptom. The problem is that the same pathogens, conditions and most importantly; the circumstances that caused the illness in the affected fish had also influenced the future health of the other more desirable fish in the system.

Finally, you should look for prospective new fish which have taut, erect fins. The dorsal fin (it’s the fin that sticks up out of the fishes’ back) should be tightly raised. The tail should be fully spread, not clamped down. Please don’t buy a fish which has clamped fins. These fish are incubators of parasitic and bacterial diseases.


*swimming actively more than 90% of the time.
*full bodied
*eating aggressively
*no wounds or sores on the fish or it’s mates.
*erect fins

Enter your email address for a free PDF of this article including its images.

Enter your Email Address

My Favorite Amazon Recommendations

Items and content will not show in "Reader View" check your browser.

This is The LCD Screen Scope
We Did The Tutorial With. I did a twenty page tutorial (Here's the tutorial) with video, audio, images and even little parasite movies to show you how to use a microscope. 

This Filter is Good For BIG Dirty Tanks
I've been wrestling with water quality with the turtles. The sponges work GREAT, but in THOSE turtle systems where they eat MICE the poops are bulky. This filter can handle it. In "Tortu's" tank, it's got an 800 gph pump and it rocks. 

PraziPro for Flukes
They nailed it. Figured out the solubility and worked out the dosing. It works. 

Buy Some Good Koi?
No, this isn't really for the 'high end' collector y'all. But for someone who isn't near a decent garden center, here are "good-to-quite-good" Koi you will like at a very good price. I know these guys personally.

Best Food, Ever
It's made for (and I discovered it for) my Blood Parrots but the small size, intense color enhancers and excellent formulation make it superb young-Koi food. Oh, and it's AMAZING on color-cichlids like Flowerhorn and Blood Parrots. 

Pro Air 60 Aerator is a VERY high output air pump pushing my whole fish room (17+ drops), and I have one at home driving everything there, and I have one as a back up. 

Formalin Malachite (Not dilute)
There are formalin malachite preparations at 10%, 22% and 37%. There's economy in the concentrates. Hard to get Prime shipping because air transport is curtailed. This is a good value on 32 ounces. 

Topical For Koi and Pond Fish Ulcers
I like 7% tincture of iodine because it stains but it's hard to hurt anything with it. Used with a WOVEN gauze, this works well to clean and disinfect a wound. Only use ONCE. Do not 'repeatedly' scrub wounds. 

Confectioner's Glaze 
Is the way to bind a medication to fish food. Gone are the days of paste food and oil. The write up is done, it's RIGHT HERE.

Koi Health & Disease
Hopefully this link takes you to the newest edition by PRIME to get it to your house the fastest. 

I have over ten of these Titanium Heaters in my fish room and at home. They're a paradigm shift in aquarium heating. They're titanium and 400W for under $30! Whaaaaaaaaat?

CyroPro by Hikari is safe and easy for Anchor Worms and Fish Lice.

Whatever heaters you use, back yourself up with a temperature controller, it'll turn on, and off your heaters. If your heater seizes "on" at least the thermostat will stop a tragedy. 

LifeGuard by Tetra is a tablet version of a tame 'chloramine-t' or 'halamid' compound that's easy to get and good on bacterial infections, in baths. 

If you're making medicated feed for a larger group of fish, this will come in handy. Dosing is available in the site. 

For me, filtration-of-choice
For aquariums, even small Koi holding facilities or small ponds. These sponge filters are cheap, easy to clean, and they clear hazes very well when used with some Accuclear or similar.

Rubber sided, round, nettable tanks
Make great hospital or quarantine facilities. They SHOULD cost about $200-300 depending on size, but this, lower quality unit (while panned in some reviews) may be good. Don't overfill and make sure it's propped up.

1200 Watt heater, on a thermostat held securely above the waterline, works GREAT as a large tank heater. That's all I'll say because there's risk of electrocution and all that. But then, even in a bucket you could get killed. Sound like fun?
I have several of these ALLIED PRECISION stainless ones that are a couple years old. Working still. 

Potassium Permanganate 
500 grams could be a lifetime supply but it's 50% more than the 100g cost wise, for 500% more amount. Dosing is in the site and the book.

What Does Ajax Eat?
I looked for something well formulated, with meat as the first ingredient. Something UNDER $2/lb and something they could deliver for free. And this was it. He looks and feels great on it.