The most common diseases we see in saltwater aquarium fish are Ich and Marine Velvet and even if you practice proper quarantine protocols, there is always a chance these ailments might show up. No matter how careful you are, its a good idea to be prepared for treatment. The good news is that a medicated treatment for active Ich and Marine Velvet uses the same exact supplies as the medicated QT protocols described in Fish Health Episode #6 with just a few critical distinctions.

To Medicate or Not To Medicate

If Ich and Marine Velvet show up in your display tank there are two things to know for certain about effective medicated treatment. You must remove ALL of your fish from the display and medicate them in a separate tank. You must also keep those fish isolated outside of the display for a particular period of time and allow your display to run fallow. The medicated treatment takes care of the active parasites on your fish and the fallow period ensures the parasites can die off in the display, preventing further infections.

This is a big undertaking and often leads aquarists down a road of pursuing alternative methods of treatment, most notable the TTM - Tank Transfer Method which does have its own anecdotal evidence of being effective. That said, there are some major PROs to using medication. 

Pros

Easier to execute, less margin for error.
Less stressful on already compromised fish.

Cons

Need to keep medication and supplies on hand and move fast because time is not on your side.

How to Medicate Saltwater Fish Infected With Ich

1. Observation

The lifecycle of Ich takes time and compared to Marine Velvet, you have some time to observe the infection in your display aquarium. If the symptoms are not severe and your fish do not appear to be getting progressively worse, you may want to consider practicing Ich Management moreover a medicated treatment. Management practices can be very effective and may be the wisest choice giving you the best results for the amount of effort put forth. 

2. Follow 80/20 Quarantine Protocol with Copper

Move the infected fish into your copper and Nitrofurazone medicated QT aquarium and proceed with the QT process for a total of 14 consecutive days from the last signs of illness. If it takes 5 days to get rid of the illness, the QT should last an additional 14 days with water changes every 3 days as described in the 80/20 QT process.

3. Fallow Period

Your tank must remain fallow (without fish) for a total of 11 weeks, 77 days to kill any parasites left in your tank. This will allow the parasites to run their life cycle completely and die out.  The lack of the host (your fish) will eventually cause the parasites to die out completely. You will need to house all of your fish in a suitable aquarium at least 10 feet away from your display, ideally in a separate room. 

How to Medicate Saltwater Fish Infected With Marine Velvet

1. Remove Fish from Display and Dip

Marine Velvet moves fast, once your notice symptoms of velvet you must act fast because it can spread throughout your tank very quickly.  Remove all of the fish from your display and proceed with the proper treatment using Formalin dip or freshwater bath. 

The most effective treatment for Marine Velvet is the use of a Formalin Dip. This approach comes with its own set of pros and cons so be sure to research first. Alternatively, you can use a freshwater dip but it may not be as effective. Hydrogen Peroxide is also being mentioned by many of the thought leaders on fish disease but is still very experimental. 

  • Use an airstone
  • Match temperature
  • Dip one fish at a time

2. Follow 80/20 Quarantine Protocol with Copper

Move affected fish into your copper and Nitrofurazone medicated QT aquarium and proceed with the QT process for a total of 14 consecutive days from the last signs of illness. If it takes 5 days to get rid of the illness, the QT should last an additional 14 days with water changes every 3 days as described in the 80/20 QT process.

3. Fallow Period

Your tank must remain fallow (without fish) for a total of 6 weeks, 42 days. This will allow the parasites to run their life cycle completely and die out. The lack of the host (your fish) will eventually cause the parasites to die out completely. You will need to house all of your fish in a suitable aquarium at least 10 feet away from your display, ideally in a separate room.

Deviations from 80/20 Quarantine

  • Target water temperatures of 70° - 72° F.  It will slow down the bacteria reproduction and parasite lifecycle.
  • The process takes a little longer than 14 days. You must get rid of the parasite first, then continue with QT treatment for an additional 14 consecutive days from the last signs of illness/parasites.
  • Nitrofurazone is critical, no optional.  This antimicrobial treatment will prevent secondary bacterial infections. Bacteria can take advantage of the skin wounds left behind by parasites and the nitrofurazone will protect the fish against those bacterial infections. 
  • After treatment, your display tank must be kept fallow which means you will need a holding tank for ALL of your fish. A Rubbermaid tub or tote can work just as well as an extra aquarium. The tank must be appropriately sized for all your fish and maintained for optimal water quality just like your display.  If a fallow period is just not an option, practicing Ich Management in your display will be the best course of action.