Back when I was a young inexperienced hobbyist I heard the term “quarantine tank” for the first time. I had no idea what it was and why it was needed at all. I was already overwhelmed with all the information out there about the hobby that I brushed it off and thought little of it. Over the next few years I lost some fish in my tanks at times and many of them within days of introduction into the aquarium. I started paying more attention to quarantine tanks and their benefits but yet did not set one up. Fast forward a few years and I’m running an aquarium service business where we are responsible for other people’s fish – a quarantine system has become a necessity. I am happy to say that now and after running this business for 12 years, we have reached a point where we are confident in our ability to quarantine fish properly and pass them on to our clients knowing they are healthy and disease-free. In this article, we will discuss the why and the how of our quarantine system and what has worked for us. We hope you can learn from our methods and be successful with quarantine as well.

Why quarantine saltwater fish?

As most of you know, the overwhelming majority of saltwater fish available in the hobby today are wild-caught species. These fish are sourced from the oceans and shipped to wholesalers in the US where they are acclimated and kept in holding tanks. The majority of wholesalers I know do a good job at acclimation, holding, and treating fish, but frankly the business model does not allow them to quarantine them for very long as high turnover dictates the existence of their business. From the wholesaler, the fish are transported to local fish stores and online sellers throughout the US. Again, the fish are kept in holding tanks at the local stores and we hope they do a good job at acclimation and holding – I couldn’t tell you for sure but I assume some do a good job and some probably do not. The point is, by the time you show up to purchase the fish, it is most likely stressed from multiple transports, medications, stressful conditions, and mishandling. Some people in the industry will tell you “the fish is eating well it’s fine” or “the fish has no visible blemishes, it’s healthy” – but I can tell you from experience that the common fish diseases like ich and flukes can be in the gills and in their mouth and you’d never know. I remember adding a great looking fish that was eating well to a client’s aquarium only to see that same fish break out with flukes and die days later. It is of great benefit to exercise some patience and make the inexpensive investment to quarantine your fish.

What are the common fish diseases to target in quarantine?

Although there are many fish diseases out there, we choose to focus on a few key diseases and it has worked well for us. The three diseases we focus on are Marine Ich, Marine Velvet, and Flukes. The symptoms of each of these diseases could be covered in another article and you could easily google them as well..but regardless of how the fish looks – we medicate and treat the fish as if they are infected. There are other diseases out there such as bacterial infections and uronema but we rarely encounter them and thus have not taken any measures to quarantine for them.

What is the filtration needed for a quarantine tank?

Our quarantine systems are set up very simply. We use an aquarium with nothing in it (no sand, rock, decorations) and a sump with plenty of biological media (plastic bioballs are best if you have room since they don’t “suck up” the medication, but we chose to use ceramic because of space limitations and it does fine…just requires more copper). We have return pumps for flow and an air pump with an airstone that is especially useful when treating with PraziPro.

What medications do we use and for how long?

We keep it quite simple…chelated copper (the brand we like is Copper Power) for ich and marine velvet. We keep a concentration of around 1.75 – 2.00. For flukes we use the very popular PraziPro product widely available and we add 1oz per 120g of water.

Our quarantine schedule goes something like this:

Day 1 – acclimate fish into the quarantine system, get copper to 1.75 – 2.00, add 1oz of prazi for every 120g of water.
Day 7 – Perform a 25% water change, again add 1oz of Prazi for every 120g of water. Test copper (it will be lower) and add more Copper Power accordingly to get the level back up to 1.75-2.00.
Day 14 – Fish are ready for clients.


Quarantining saltwater fish is neither difficult nor expensive. It does require some patience and basic knowledge which we hope we just provided you :) Remember to observe the fish’s behavior and feed them well and follow our guidelines. It is worth the time and effort and will surely save you heartache and disappointment down the road.