I receive quite a few calls from folks with Marine Reef systems containing live rock, corals and sponges. The biggest problem these folks face, [aside from getting a consistent reading on their Redox Meters] is treating probable parasite problems in their fish, while sparing the lives of their corals, sponges and other ornaments as collected from the reefs.

Some basics of this problem are that the reef keeper is impaired because Copper cannot be employed with these invertebrates. Copper is also a major risk with many, if not most, of the Sharks, Skates and Rays.

Therefore, I recommend depopulation and/or freshwater dipping for the cure of these fish.

Leaving the marine system depopulated for the duration of one complete life cycle of the suspected parasite usually solves the problem without having to use a toxic compound in the system.

Let's talk about these components of cure individually.

The first component of cure is depopulation. Without a host to live on, many parasites perish. While unreliable in some parasitisms, 21 days depopulation will eliminate most parasites from a sensitive reef system, particularly if you consider the second component of care:

The second component is the raising of the temperature in a given system, to speed up the life cycle of the parasite you are treating. As a simple example, Cryptokaryon irritans will embed in the skin of a fish, causing the characteristic white spot. Later, the parasite has matured, and ruptures from the skin to drop reproductive forms to the bottom of the system. In this phase, medications can eliminate the parasite. While under the skin, the parasite is immune. Aquarists can use temperature to push the parasite out into the water where it can be killed. But in reef systems where few medicaments are prudent to use, and where we have to rely on simple depopulation, warmer waters will hasten the maturation of the parasite and starve it out quicker. Individual considerations of this type of adjunctive therapy would include the knowledge of which corals and other invertebrates that cannot tolerate the higher temperatures.

A third component of this care could be the use of copper in the isolation system containing the fish. Basically, treating with copper will clear the fish of their parasites, and then it is just a waiting game while parasites in the mother system mature and starve.

Copper (from Copper sulfate) would be used at a level of 0.2 ppm at all times during the treatment period. Attention should be given to the following facts:

* Copper can inhibit denitrification, by killing some of the nitrifying bacteria.

* Copper is immunosuppressive to fish, reducing their immunity with protracted use.

* Copper can be adsorbed by coral skeletons and gravels, then later: Can be leached out into the water again, with fatal results, usually right after you just bought an expensive new invertebrate specimen.

A fourth component of this care is the employment of a UV light. This is a high-tech piece of equipment that can reduce the incidence of parasitisms in ornamental Marine specimens, simply by killing free forms of the various pathogens as they stream through the light. It should be noted here that the amount of light it takes to kill different parasites varies! A free form of Crypto will take more or less than Amyloodinium. Bulbs are characterized by Wattage, and the Ultraviolet sterilizer has adjustable flow rates. The "power" of an Ultraviolet sterilizer is a combination of the wattage the bulb produces, and the flow rate (in seconds) over the bulb. The term for all this is microwatt/sec

A conservative amount of light to try to achieve would be somewhere around 200,000 micro-watt seconds. This is a fairly slow flow over one or more fairly powerful bulbs. Many retailers would say that this is excessive. Part of that problem is they want your investment in UV apparatus to be affordable, and for large systems or in this case where you want adequate control of most pathogens, it may not be. As a side note, simple suspended green algae requires a mere 34,000 microwatt/sec for elimination. The manufacturers data sheet can help you determine how to set the flow over their particular unit to get that power.

A fifth and final asset in the treatment of diseases in Reef systems would be the judicious use of Freshwater dips to save fish badly affected by certain parasites, not the least of which includes Trematodes (Black Ich), which is not usually Copper responsive, and Brooklynella. One way to incorporate this would be to remove all your fish to an isolation hospital with 0.2 ppm copper but before placing the fish in isolation, you could freshwater dip it.

Freshwater dips are made with tap water (or aged water) at the same temperature as the main system, and the same pH. pH can be brought up using Seachem's Marine buffer. It contributes nothing to salinity, but makes the pH equal between the main and dip water. The amount to use is traditionally 1/2 to 1 teaspoon per quart of water in a plastic fishbag, so the fish can be floated in the main system with its friends while being dipped. The fish is placed in the freshwater dip for a few minutes, or until it seems to be struggling. Do not wait until it is near death, or flipped over, or you could cause the fish to be overwhelmed with death, resulting in a permanent and catastrophic failure to breathe, swim, or entertain you in any way. <g>

One side note: Do not add the fishes' dip water back into the main system. Some parasites (one example: Microcotyle) can revive‰ after re-introduction into the saline environment.

So in summary: The treatment of a sensitive reef system for parasites would include any (or all) of the following:

* 1) Depopulation of the fish hosts for 14-21 days

* 2) Treatment of the fish in quarantine with Copper Sulfate at 0.2 ppm (except elasmobranchs.)

* 3) Treatment of the most seriously affected fish for short term recovery in pH and temperature balanced freshwater dips.

* 4) Use of Ultraviolet sterilization at about 200,000 mws to decrease transmission of infectious forms of pathogens from fish to fish.

* 5) Increasing the heat in the system (to 82-84 degrees) may hasten clearance during depopulation. (Caution with certain species.)

There are some products marketed now that claim to be safe with invertebrates. Interestingly, they do not seem to work, and do seem to harm filter bacteria. It seems like an opportunity to concurrently shut down your filter while deciding on the next step to take.