Little is really known about many of the maladies that strike our captive fish, and what we can and cannot do. Recognition, diagnosis and effective treatment is the biggest problem facing even the most experienced of aquarists. Here is some info, based on almost 25 years of observation, experimentation and study. This is by no means a scientific exposition, but basically anectdotal and experiential.
BLOATING Many fish, unfortunately, come with internal parasites and infections, largely unknown and unstudied. Little if anything can be done, except, if the fish is still eating, medicated flake foods, can be tried. Tetra� brand makes a line of medicated foods. Many fish, just prior to death, also bloat up. Its been my experience, more so, with the dwarf Centropyge Angelfish, and angelfish in general. One of the first signs of trouble is abnormal looking or stringy feces.
BLACK SPOT DISEASE Parasitic Nematode worms, approx 1mm in size, seen on the bodies of Tangs, but also Butterflyfish and Angels. Most prevalent with Yellow Tangs. Also known as "Black Ich". This is a parasitic worm that comes in with many fish, especially Yellow Tangs. These parasites are also known to be introduced with LiveSand. Treatment consists of either short term Hyposalinity, gradually exchanging SW for FW of the same temp and pH, until almost all FW, which kills the parasite, for a duration of 15 minutes, or Long term bath using a Formalin based medication, generally lasting several days. Note that all treatments need to be done in a Hospital Tank, and Formalin is a powerful anti-bacterial, that will destroy biological filters. Because the parasite also resides in the substrate, re-infections are likely. The best precautions are careful observations of the fish BEFORE purchase, and QUARANTINE, prior to introduction to one's main aquarium(s).
LYMPHOCYSTIS Characterized by whitish clumps, like small grapes, generally seen on the fins, but sometimes on other parts of the body. This is caused by a virus, and is generally a result of poor water conditions and stress. As is true of many viruses, no known treatment exists. It seldom, if any, causes any distress on the fish, and by maintaining the highest of water quality, and foods, generally disappears. Very large clumps can be removed by netting the fish, and carefully cutting portions away. Care should be taken not to further damage the fish. In virtually all cases, the disease spontaneously disappears.
AMYLOODINIUM OCELLATUM Used to be called Oodinium, and changed, as not to be confused with its FW counterpart. This parasite is a dinoflagellate. related more to diatoms, then protozoans (like Cryptocaryon irritans) and considerably smaller in size. Like SW Ick, its an obligate parasite and needs a fish to complete its life cycle. It basically has three stages, the infective free swimming stage, the feeding stage, and the reproductive cystic stage.
In its free swimming stage, if it does not find a host within 24 hours, it dies. However, researchers have found at least one strain, which remained infective for at least four weeks. Similar in its reproductive ability to exponentially divide its self, like Ich, it can quickly overwhelm its host. Infective cycles can be as little as 72 hours, depending on aquarium tempertures, and as long as 6 or 7 days.
Because of its size and infective activity, generally, the first sign is rapid breathing, lethargy, and hanging out at the surface, or in the flow of a water return source. Its at this point that treatment is the most effective. Once signs of the parasite become visible, a general hazy, white powdery, dust like covering of the skin, which is actually a combination of mucous and epiphellium (skin) being sloughed (eaten) off, death is generally imminent. It is highly infective and spreads to all fish quickly. Its also known to produce a deadly toxin, where death has occured without any other characteristic signs.
At the first sign (rapid breathing) treatment needs to be started IMMEDIATELY. The ONLY effective treatment known is Copper. In a Reef tank, ALL fish MUST be removed, to a Hospital tank, whether displaying any symptoms or not, and a Copper bath regimen initiated. As in all cases, where treatment is carried out away from the main aquarium, particular emphasis must be placed on Biological filtration, and the processing of ammonia. In a FO, without LiveRock and/or denitrifying substrates, either Chelated or Complexed Copper must be used, at its maximum recommended strength, monitored daily, for a minimum of 4 to 6 weeks. Because of its resiliency, any infections observed in a Reef system, where the fish have been removed, the tank must remain fish free for 8 weeks, to absolutely be sure that no more infective dinospores survive.
In my own experiences and observations fortunately, I have only witnessed a hand full of cases, and personally, only recall treating one or two myself, in the last ten years. In either event, the first sign was rapid breathing, generally within 3 days of the introduction of a new fish, and where most of the other fish had some signs of distress. CopperSafe was immediately added, at full strength, to the tank, and within 24 hours, the initial sympton (rapid breathing and lethargy) disappeared, and never re-occured.
In cases where the characteristic white haziness appeared (gratefully, not in my tanks!) death occured within several hours, and treatment was ineffective. As in the case of Cryptocaryon (white spot disease) Copper is only effective against the freeswimming infective stage. Once its characteristic signs appear, it is just too late! The parasite is generally transmitted by a fish, but its cysts can come in with invertebrates, LiveRock and LiveSand, and its spores are even known to travel in the air, just like diatoms. Prevention is much harder with this parasite, as even Quarantine is not always effective. Judicious observation, and swift action are the best that can be done, with immediate applications of Copper.