Shane's World Right Arrow CatfishologyRight Arrow The Catfish Basics Series, Part 7 • Selection, Acclimatization, and Quarantine

Article © Shane Linder, uploaded January 01, 2002.

Failure to properly quarantine new acquisitions probably accounts for most catfish disease disasters experienced by aquarists. This is often because it is difficult to monitor new arrivals in a display tank and make sure they are healthy and eating. Also, if they are diseased, they may not only perish, but spread their malady to the rest of the display aquarium. Take a quick look through the Forums here and you will see several posts that follow the same sad story of a newly purchased fish bringing parasites, fungus, and/or a bacterial infection to someone’s beloved display tank. The pleasure of getting up the next day to observe your new fish turns to horror when you realize the new acquisition has brought ick with it.

Try to watch any fish that you plan to purchase for a few minutes at the retailer. Is it too active, listless, having trouble swimming, or not acting normal? Does it scratch it self on the substrate or hang close to the filter outflow? These are all potential bad signs. Once you have selected the fish, look it over very carefully in a specimen container or plastic bag. Are the fins intact? Some wear and tear is normal from shipping and fighting with tank mates, but damaged hard fin rays will rarely grow back. Are the eyes clear, the mouth free of damage and the barbels in a healthy state? Take a close look at the anal region. If it is swollen or red it could mean the fish has an internal infection and these are very difficult to treat. Specifically, with regards to loricariids, cloudy or "blue-gray" eyes often mean that the fish was treated with damaging medications that have caused cataracts. These will not heal, but most plecos still do fine with limited vision. Watch the fish breathe as well before it is netted. Loricariids that are breathing very rapidly often have gill parasites. Finally, many blackwater catfishes, loricariids especially, are very susceptible to bacterial infections. This is because acidic blackwaters in nature usually have a very low bacterial content. These infections often manifest themselves as sores, odd growths or a white to grayish look to the skin.

Getting the fish out of the bag as fast as possible when you get home is the most important thing. Several studies have shown that the stress and brain damage caused by the lack of air and high ammonia levels in a bag are far, far more stressful to a fish than a rapid change in pH, hardness, or temperature. There is never any reason to float a fish in a bag. It does more harm than good. Fish are hardly affected by minor temperature changes. A good rain in the Amazon can drop the temperature several degrees in minutes.

Here is the acclimatization system I use:

  1. Hang a clear plastic specimen container in the quarantine tank and dump in the new arrivals and their original water. If you do not have a specimen container, attach the bag to the aquarium with clothesline clips.
  2. Add about 20 percent of the container's volume using a cup of water from the quarantine tank. Keep adding 20 percent or so every 5 minutes. Let the specimen container overflow back into the quarantine tank.
  3. After about five of these changes over 25-30 minutes, just let the specimen container or bag sink to the bottom of the quarantine tank. The new acquisitions will swim out when they are comfortable.

Never dump a bag containing fish directly into a tank. Over the years I have seen several fish immediately swim full speed into a tank wall or piece of décor and kill themselves. Let them swim out of the bag or specimen container at their own speed. This also gives them time to figure out where the walls and obstacles are.

Unless you predominately purchase very big fishes, a five to ten gallon aquarium will work well as a quarantine tank. The tank’s filtration should be both mechanical and chemical. Do not worry about establishing the biological cycle. Occasional use of medications in the quarantine tank will wipe out the beneficial bacteria. The quarantine tank should be kept clean via mechanical and chemical filtration coupled with small frequent water changes. The chemical aspect is needed for removing medication from the tank’s water quickly if the fish have a poor reaction to a medication. In addition to a good filter, the tank should have a reliable heater and a light. The light is important so that you can see the fish in quarantine easily and note any changes quickly. Décor should be limited to a few plastic plants and caves. The tank should not have any type of substrate. The bottom glass of the tank can be covered with paper or a piece of plastic from underneath so the fish can not see through it. The only organic décor should be a piece of driftwood if the fish being acclimatized are wood eaters.

While in quarantine, ten percent water changes should be carried out daily for the first week. I have observed that these frequent water changes really help new fish to adapt more quickly. After the first week, it is ok to do slightly larger water changes every three to four days instead. The quarantine tank will also need a tight fitting cover. Most catfish suicide jumps take place shortly after purchase or capture while the fish is exploring the limits of its new habitat. Leave the quarantine tank running all the time. When you are not planning on purchasing new livestock it can double as a hospital or fry tank for raising young fishes. Beware, however, as this is usually the start of Multiple Tank Syndrome (MTS). Once the quarantine tank becomes a hospital tank you will surely see a new catfish you have to have and need to buy another tank to act as a quarantine tank. Once this has happened the aquarists has become an MTS carrier. MTS seems to produce a feeling of elation in the aquarist it affects and its negative impacts are only felt by roommates, spouses and children who are forced to sacrifice some of their living space for more catfish aquariums.

A Few Notes:
Do not medicate fish in quarantine "just to be safe." They have already been through this treatment at the exporters, importers, and possibly retailers. Melafix is the exception as it is fairly benign and helps fish get over the ammonia burns associated with transport faster.

Wild caught fish can be given a bath in saltwater to remove any parasites they may have. Just a few minutes in full strength seawater will do the trick (or a freshwater bath for marine catfishes). Do not feed the new acquisitions for a day or two. They usually will not eat and the food will only foul the water. It is normal for many new catfishes not to want to eat for a few days. A healthy appetite will also make the fish more likely to accept the foods you offer. Do not "stack"l fishes in quarantine. If new acquisitions are added to the quarantine tank the quarantine period must start again from the beginning.

Lastly, leave the fish in quarantine as long as possible. I know it is hard to do, especially when you already have their new home all set up, but it is well worth the wait. Monitoring and treating a few catfish in a plain ten gallon tank is much easier than in a fifty five gallon display tank full of other precious fishes. So when can they go into their new home? When you are confident that they are healthy, well adapted and eating a variety of foods. I would recommend two to three weeks quarantine for catfishes that adapt quickly and four to six weeks for catfishes that need some time to heal, put on some weight, or for species that are known to be sensitive in captivity.

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