I got this question from Tim Gray of Beeville, Texas, that I think is very interesting, so I’m blogging about it:
“Mr. Clapsaddle, could you explain your quarantine practices when bringing in wild stock or from unknown sources?”
Here was my response:
This is a great topic. We have two large recirculating systems. On a daily basis we transfer fish, plants, livefoods, and water between the systems. Also, we use intensive culture techniques under which our 800 vats of fish are very crowded. Any infectious disease organism would have a heyday in our systems. So, avoidance of introduction of organisms such as Chilodenella or ich is critical.
We treat fish from sources we don’t completely trust or fish that we collect in the wild exactly the same. First of all we expect the fish to be loaded with internal parasites and to have some external parasites. Incoming breeding stock unknown sources or from the wild are placed into tanks that are off and isolated from our systems. During the summer we use outside 300 gallon vats placed in the sun. During the winter we use 40 gallon tanks in our warehouse and equip them with heaters. We prefer to use the outside vats for several reasons. One, water changes are easier. Two, they have more water volume. Three, sunlight itself is a disinfectant. Four, they have healthy populations of creatures such as Paramecium that feed upon some stages of external parasites and [nternal parasites that have external stages. Fifth, we don’t have aerate or filter these large vats. We only use the 40 gallon aquaria when it’s too cold outside or for very small numbers of very small fish.
Once the quarantined fish are in their vat, we feed them with fish food grinds of an appropriate size for the fish from Simple Pet Products. These foods are a bit oily and we coat them with powdered praziquantel, a commonly used wormer for vertebrates. We feed the the coated food every other day for a week. Next we treat the vats with 3-6 ppt NaCl (we use solar salt, but rock salt will work). To achieve 3 ppt salt simply calculate the volume of water in liters in the vat (3.8 L per gallon) and multiply by 3. We add this amount of the salt in grams directly into the tank. The salt dissolves slowly and gives the fish time to adapt. We also add 1 ml of a 37% formaldehyde/malachite green solution per ten gallons (or 38 L). This solution is made by adding 1.4 g of malachite green to 380 ml of 37% formaldehyde. This solution lasts forever if kept in brown bottles stored in the refrigerator. The vat is treated with this solution on the first and seventh days. We usually change 50% of water before the second treatment, but it’s not necessary if the vat is outside in the sunlight. If we change half the water, we then add half the amount of salt as the first salt treatment. Let me discuss the salt concentration for a moment. I prefer to use 6 ppt rather than the lower does of 3 ppt. I’ve found that even soft water fish will tolerate the higher dosage and the higher dosage is more effective against parasites. That said, for high cost, difficult to find soft water species I’ll use the lower dosage and not take any chances.
Another factor to consider when using prophylactic treatments is the health status of the fish. If the fish are in really bad shape, I delay treating them for a few days, especially if a small number of fish are placed in a 300 tank. Any parasites are likely to be diluted by the large volume of water and giving the fish a chance to recover somewhat before treating is a good idea. Reinfection from parasites will take a few days so there is time to delay treatment.
After a couple of weeks, I often place some fish from our systems in with the new fish. If nothing bad happens after about a month, I deem the new fish safe to introduce.
These procedures aren’t always perfect. When something slips through we have to treat our whole 75,000 gallon systems with salt, malachite green, and formaldehyde. This has only happened twice over the last 13 years.