Fish Diseases 101
The purpose of this article is to provide a quick reference for identifying both “Common Diseases” and “Not So Common Diseases” afflicting saltwater fish. It is by no means a comprehensive list, but should cover the vast majority of fish diseases encountered by the average hobbyist. Each group of diseases is listed alphabetically.
Once you have identified the disease you think you are dealing with, click here to view more information about available treatment options: https://www.reef2reef.com/forums/fi...is/189658-treatment-options-my-two-cents.html
Common Diseases
Ammonia Burn/fish injuries:
Symptoms - This appears as redness around the gill areas. The cause is exposure to ammonia, which can happen during acclimation, quarantine, or when a fish is placed in an aquarium which has not been completely cycled. Prolonged ammonia exposure can damage a fish’s gills, liver and kidneys, usually resulting in death within a few days.
Treatment options - Malachite Green or Methylene Blue, used either in a quarantine tank or as a bath treatment. Both help heal wounds, including gill damage from ammonia poisoning. For eye and other injuries, you can also dose Epsom salt (1 tablespoon per 5 gals). Epsom salt is magnesium sulfate, making it reef safe.
Bacterial infections:
Symptoms - Sometimes it's self-describing: Popeye/cloudy eyes, fin & tail rot, dropsy (bloated fish), etc. But some other bacterial infections, such as furunculosis, hemorrhagic septicemia, etc., can have varying visible symptoms. Any redness or open sores/wounds on a fish should be viewed with suspicion. Also, a white film or fungus-looking growth may denote a bacterial infection. It’s important to note that in many cases a bacterial infection is usually secondary in nature to a parasitic infestation such as ich, meaning if a fish has been battling ich for a while then his immune system has been lowered. This makes infection more likely for many opportunistic, harmful bacteria.
Treatment options - Broad spectrum antibiotic medication i.e. one that treats both gram-positive and gram-negative bacterial diseases. Examples of this include Furan-2, Kanamycin aka Seachem Kanaplex, Nitrofuracin Green Powder, Triple Sulfa Powder, or a combination of using both Erythromycin & Minocycline. The latter can be accomplished (albeit expensively) by using freshwater Maracyn 1 & 2 and then doubling the dosage for saltwater use. When battling a particularly nasty bacterial infection, combining Furan-2, Kanaplex and metronidazole (ex. Seachem MetroPlex) can be very effective (and safe). Props to “hedgedrew” for enlightening me of this.
Brooklynella:
Symptoms – This is most often seen in clownfish, but it can afflict any fish. The fish’s skin will appear to be peeling or sloughing off, oftentimes causing excessive white mucous to form around the affected area(s).
Treatment options - Formalin or acriflavine bath, followed by additional baths (as needed - but give the fish a day to recuperate in-between baths). You can use formalin in a QT (at a much lower concentration than the bath), but great care must be taken to provide plenty of gas exchange as formalin will quickly deplete the water of oxygen. For this reason, doing baths is the safer option as the fish can be pulled from the formalin if showing signs of distress. Acriflavine is probably the better option for in-tank QT use.
The following products contain formalin: Formalin-MS (preferred), Quick Cure, Aquarium Solutions Ich-X, Kordon Rid-Ich Plus.
Acriflavine can be found in Acriflavine-MS (preferred) and Ruby Reef Rally.
Metronidazole (exs. Seachem MetroPlex, Metro-MS, Hikari Metro+) is considered an alternative treatment for brook. A freshwater dip may provide temporary relief if you are unable to locate any of the aforementioned medications right away. Some even claim total eradication of the disease is possible just by performing multiple FW dips on the fish.
Flukes:
Symptoms - Flukes are parasitic flatworms which harbor mainly inside the gills. Physical evidence of flukes is usually not visible; however at least one genus likes to target the face & eyes, so you may notice visible symptoms in those areas. Behavioral symptoms such as yawning, head twitching, scratching (targeting the gill area) and lethargy are much more common. As the disease progresses, the worms move to the eyes, and this is when you may see visible symptoms (cloudy eyes). However, you can confirm the presence of flukes at any time by performing a freshwater dip. At around the 3-4 minute mark, you will see tiny white worms fall out of a fish (especially out of the gills) if a fish has flukes. The worms will settle to the bottom, so you can use a flashlight to look for them there as well. A dark/black bucket is preferred for the freshwater dip, as that makes the white flukes easier to see.
Treatment options - Prazipro. Performing a freshwater dip will provide temporary relief, but two rounds of Prazipro (5-7 days apart) is usually required to eradicate flukes. Formalin may be used as an alternative treatment. Hyposalinity – Scientific research also showed hyposalinity at 15 ppt for 2 days eliminated juvenile and adult flukes. When maintained for 5 days, egg hatching was prevented.
Head & Lateral Line Erosion "HLLE":
Symptoms - HLLE literally looks as though the skin is rotting or peeling off the fish. Affected areas usually include the face and lateral line, and may be white in color.
Treatment options - This is more of a condition than an actual disease. Since no one can agree on the exact cause, all you can do is address all of the following theories regarding HLLE:
1) Stray voltage - Use a titanium ground probe & test your tank for stray voltage.
2) Running carbon - Don’t use it, or use only premium grade carbon.
3) Nutritional deficiency - Feed high quality nutritional foods. Some have had success reversing the effects of HLLE by soaking food in “fish vitamins” and also feeding nori.
Ich (Cryptocaryon irritans):
Symptoms - Ich looks like salt or sugar-like “sprinkles” on the body or fins, usually more “here & there” as opposed to the fish being completely covered in them (see Velvet). Other symptoms include scratching on rocks/sand, head twitching and heavy breathing.
Treatment options - Copper, Chloroquine phosphate, tank transfer method, or hyposalinity.
Lymphocystis:
Symptoms - Lymphocystis appears as a white or beige colored cauliflower-like growth that usually starts on the fins and spines and sometimes spreads to the body. Initially it may be small (looks like ich), and then grows in size (which is how you know it’s not ich). Lympho is a virus that many fish carry for life. Fortunately, it is rarely fatal or even harmful to the fish, and symptoms will come and go.
Treatment options - No known cure or treatment exists. However, feeding vitamin-enriched foods and maintaining pristine water conditions may expedite the “going away” process.
Velvet (Amyloodinium):
Symptoms - Because velvet can be such a fast killer, key behavioral symptoms will often prelude visible ones. A fish with velvet may breathe heavy, seek relief by swimming into the flow of a powerhead and act reclusive (velvet makes them sensitive to light).
If visible symptoms do manifest; velvet appears the same as ich, except the fish will usually be covered in “dust.” This dust may look gold colored if viewed at the right angle and under the right spectrum of light. Velvet is often misdiagnosed as ich and is the main “tank killer” in our hobby. It can wipe out all your fish in less than 72 hours and cannot usually be “managed” as ich sometimes is.
Treatment options - Chloroquine phosphate is the treatment of choice for velvet, but copper also works if symptoms are caught early on. Tank transfer and hypo does not work with velvet. A freshwater dip or formalin bath is recommended before treatment begins, due to the severity of this disease; however these would only provide temporary relief and will not eradicate velvet.
Not So Common Diseases
Anchor Worms:
Symptoms - Anchor worms appear as red or inflamed skin irritations with little whitish-green worms sticking out. The tail of the worm makes a V. Often a fish will rub on rocks and sand in an attempt to dislodge the worm(s).
Treatment options - You have to manually remove all the anchor worms by using tweezers. Afterwards, apply a topical antibiotic to the affected areas. Dimilin will eradicate anchor worm eggs in a quarantine tank, but the medication is not reef safe.
Black Ich:
Symptoms - This looks like tiny black dots on the body or fins. Black ich is caused by an infestation of turbellarian flatworms and is mostly seen in tangs. It is “ich” in name only and requires an entirely different treatment than Cryptocaryon irritans.
Treatment options – Prazipro, or formalin bath.
Internal/intestinal parasites:
Symptoms - Internal parasites are also “worms,” but these target a fish’s intestines. As a result, the main symptom is white stringy poop. It has to be white; brown stringy poop, for example, can just mean intestinal irritation which requires no treatment.
Treatment options - API General Cure (a medication containing both praziquantel and metronidazole). Some species of internal worms are resistant to prazi, while others are resistant to metro, but usually not both. :wink: Seachem MetroPlex can be dosed directly in QT, or soaking fish food with it provides an alternative (and reef safe) treatment option. Two other available options are: Paracide-X (mixed in food) and Paracide-D (in-tank treatment).
Isopod Parasites (very rare):
Symptoms - These are more frequently seen on shrimp, but some species target fish. They are nocturnal and difficult to distinguish from beneficial amphipods you may have in your aquarium. So, the best way to detect their presence is to watch your fish for evidence of their existence. You will notice bite marks (it’s most evident on any yellow fish), or even the alarming sight of some attached to your fish when the lights first come on. There are even “tongue eating isopods.”
Treatment options - First, remove all fish (except one easy-to-catch yellow fish). The yellow fish will be used as “bait” to draw out and remove the isopods from the fish’s skin (by using tweezers). Rinse & repeat until there is no more evidence of fish-attacking isopods in your tank.
Red Sores:
Symptoms - These are most commonly seen on butterflyfish. Red sores may be a symptom of a bacterial infection or something else entirely.
Treatment options - Nitrofurazone (active ingredient found in Furan-2 and Nitrofuracin Green Powder).
Swim Bladder Disorder/fish constipation:
Symptoms - Both of these have identical symptoms, but fish with swim bladder disorder generally do not survive. So your best bet is to treat for constipation and hope for the best. The fish will swim erratically, and appear to have difficulty maintaining its equilibrium. It may appear buoyant at the surface of the water, sometimes swimming in circles.
Treatment options - Feed 1 or 2 peeled boiled green peas (same kind you & I eat). Repeat daily even if the fish’s condition improves. The fiber contained in the peas will help “push things out.” If dealing with a fish that refuses to eat, you can try Epsom salt (as a laxative) or an antibiotic such as Kanamycin (aka Seachem Kanaplex) that lists diarrhea as a possible side effect.
Uronema marinum:
Symptoms - These are the red sores often seen on chromis damsels. The disease seems mostly confined to damsels and clownfish, but I have seen some exceptions to that.
Treatment options - This is a very difficult disease to treat. Possible treatment options include: Metronidazole (ex. Seachem MetroPlex), acriflavine (ex. Acriflavine-MS), Chloroquine phosphate and copper. The problem is the fish can never be returned to the infected tank from which it came. Uronema is a “free living” parasite which does not require a fish host. So, going fallow will not eradicate it. Most fish seem protected from it via their natural immune system; but for some reason, chromis and some other fish are not always afforded this protection. Once a tank has Uronema, it must be assumed that the disease can survive in there almost indefinitely.
Formalin bath or freshwater dip may provide temporary relief for Uronema.
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