Buying and Introducing New Fish
A cautionary tale...
There are a number of 'Golden Rules' often put forward as to what you should and should not
do when purchasing new fish and introducing them to your aquarium. These usually include:
- Obtain your fish from a known dealer, preferably after they have been in the store for a
week or two, so that any disease should have shown itself.
- Purchase only healthy looking fish from tanks where there are no dead or ill-looking fish.
- Use a quarantine tank if possible. This will allow the fish to be observed for any signs
of disease before releasing into a tank full of healthy fish.
These things seem to be common sense. But how many people have been tempted by a fish that
they "have been trying to find for ages" and buy it on impulse from a store they don't usually
purchase from, and have no idea how long the fish has been in the store? Or worse, purchase it
from a tank with dead or dying fish in, because the one they want "looks OK". And how many people
use a quarantine tank, particularly when new to the hobby or maintaining only one tank in the
If you break one of these rules occasionally, or perhaps never quarantine because you buy
only from one local trusted dealer, it is quite possible you may get away without suffering
any drastic consequences. But then again...
On one occasion, I broke two, or possibly three, of the Golden Rules. I had been keeping fish for
over a year at this time, and should have known better. Even the general aquarium books I had read
early on cautioned against such mistakes - but sometimes learning the hard way reinforces what you
already know, in such a way that the knowledge is applied more rigorously next time.
So, I had my first incarnation of my South American catfish tank set up. It contained 7 Corydoras,
a Gold Nugget plec, two Pimellodus pictus and three adult angelfish, which included a breeding pair.
I wanted to add two more pictus catfish, as I had read that they were more active by day in a small group.
My usual store hadn't had any in for a while. One weekend, I was purchasing some granular food that
was only stocked locally by a small general pet store, when I noticed a couple of pictus cats in one
of their dozen or so fishtanks. I had never bought fish from them before as they stocked only a handful
of common community fish. But on this occcasion they had the two pictus cats I was after...
So, although (as usual) a few of the fish in their tanks looked a bit off-colour and sluggish, I bought
the two pictus catfish. I didn't think they looked as vibrant and healthy as the two I already had, but
of course they were in the shop tank, they would soon perk up in better water conditions and with a
At this time, the only small tank that would normally be spare had some baby Panda corydoras in, so the
two new pictus cats went straight into the main catfish tank. I remember thinking in the next couple of
days that they never looked too well after being added. All the other fish were healthy and behaving
normally however, and the usual water tests were OK. A further factor came into play here, I was away
from home overnight and didn't have chance to check the tank for two days as a consequence. When I did,
I noticed something was wrong.
Several of the fish were behaving abnormally, and I noticed tiny white sugar-grain like spots
on several of the fish - the characteristic sign of White Spot (Ichthyophthirius) disease. I started
treating with a commercial anti-White Spot remedy, but I believe the disease was too advanced and/or
there was a secondary infection at work because several fish died over the next few days with badly
deteriorated fins and sores present.
So altogether, I lost all four pictus cats, the Gold Nugget plec and three beautiful adult Angels including
my spawning pair. Only the corydoras catfish survived. These days I tend to buy from only one good quality
local supplier, and I often use a simple quarantine tank now...