Fish Health
Like any pet, fish suffer from pests, diseases and health problems. There are several that occur commonly, so here's an overview to help diagnose your fishes' health.
Physical Damage
Neon Tetra Disease
Physical Damage
Physical damage can result from rough handling, fighting, importation and parasitic infections. If your fish has a parasite, it will often scratch against rough surfaces and may suffer damage. Usually you will signs like missing scales, split or frayed fins, listlessness or perhaps even missing eyes! Eyes are an easy target for attack. It's important to watch out for these signs, because if left unchecked your fish could become affected by one of the conditions listed below. To prevent damage, take great care when handling your fish, and try to separate any trouble-makers or aggressive fish. If one of your fish is consistently aggressive, you may need to talk to your local fish store about exchanging it for something else. Try to choose your livestock wisely at the outset - find out whether any of the fish you want to keep are unsuitable for a community tank. For freshwater fish, you can treat damage with an aquatic antibacterial. You will need to isolate very badly affected fish in order to this, even if you have a pond. Marine fish are best treated in isolation outside the aquarium at all times, no matter how minor the infection. If your fish has a deep wound, you can wipe it directly with and antiseptic, such as mercurochrome. Making sure you thoroughly clean any equipment you are using with an aquatic disinfectant will prevent further contamination.
Neon Tetra Disease
This infection is caused by a parasite Fish may carry minor infections with no obvious symptoms. However, badly affected fish lose a lot of colouration, become emaciated, develop a curvature of the spine or exhibit unusual swimming behaviour. The parasite passes between fish, but the spores can live without a host for a short time. Water quality is a major factor in the occurrence of this disease. There are chemicals available for the treatment of this condition, although none are completely effective. Fish that appear to have recovered can still carry the parasite. In order to prevent further contamination, dead fish must be removed so that the other fish don't eat the remains. If your fish becomes affected, it is advisable to completely empty and strip down your tank, thoroughly disinfect it and restock it with new decorations and substrate and new fish from another source.
White Spot (Saltwater Ich)
This disease is easily detected as tiny white spots show up all over your fish's body and fins. It's caused by a parasite (present under each spot), which will make the fish itch. A fish with this condition can often be seen scratching on rocks or gravel. A heavy infestation will leave your fish looking as if it has been sprinkled with salt. Ichthyophthirius is capable of affecting almost all freshwater fish (tropical and marine). Crytocaryon affects marine species, but only in warm water above 18C. If this disease occurs, it is often best to remove the affected fish into quarantine for treatment. There are copper-based treatments you can use for marine fish, but beware, these treatments are fatal to marine invertebrates. If you choose this treatment, you must quarantine your fish first. A way to deal with ich naturally in a marine tank is by reducing the salt density. A lower salt content is less favourable for the parasites. Be careful to lower it gradually and within the safe parameters, and watch the effect on things like corals. You can also boost your fishes' immune system with garlic when necessary.
Anchor Worm
This is another parasite, which buries its head in the fishes' body, leaving it's posterior and egg sacs visible. The worms can bury themselves into the fish's internal organs, and an extreme case can result in weight loss or even death. Chemical remedies are often used for this parasite, as they can be added to tank or pondwater. Anchor worm is a common problem in garden ponds in summertime, rather than the indoor aquarium. In addition to the treatment, you will need to carefully remove the adult parasites from your fish, by gripping the parasite as close to the fish's body as possible and pulling it out swiftly. Treat the wound with an approved topical antiseptic, and observe your fish carefully - you may need to repeat this process after a week or so. Discuss any chemical treatment with your local fish store before you use it, and be sure you know it's safe for every species of fish you have in the affected water. You may need to quarantine some while treatment takes place.
Fungus
This is very easy to spot, as cotton-wool-like growths appear on your fish's fins and body. External fungal problems are rarely reported on marine fish, but affect brackish and freshwater fish. Initially quite minor, this fungus will spread if left untreated, and can kill your fish and/or its eggs. It can be transmitted between fish, and although the mucus on fish scales usually provides protection, injured fish will be more susceptible. A fish that has already been sick will also be at a higher risk. Poor water quality or sudden changes in temperature can put fish at risk of fungal infection. Usually you would use a fungus treatment that is added to the tank. This is fine for a minor infection, but in severe cases quarantine is required. If you have eggs in your tank, be sure to remove all dead (clear) fish eggs to prevent infestation. If you want to treat your eggs, look for a product which is suitable.
Dropsy
This disease tends to give fish a pinecone effect, with their abdomens bloated and distended and the scales sticking out. Other signs are long, pale fecal casts, ulcers, pale gills and bulging eyes. This is caused by bacterial and/or viral infections, metabolic and nutritional disorders. Dropsy is likely to affect fish in a poor condition but can affect a few fish in a healthy tank as well. As the causes of this condition are unclear, it makes treatment very difficult. The best way to deal with this is to look at your fish's health, diet and water quality and make sure everything is balanced. In severe cases quarantine and a broad-spectrum antibiotic may be required.
Gill Flukes
This isn't always easy to spot early, but the fish's gills will be covered in mucus. Gill problems may be caused by poor water conditions or fungal infections. Water changes are crucial to reduce this problem. Overcrowding is often present when gill flukes occur, so check your stock and make sure your fish have enough space. Testing your water quality will give you an indication of the situation. Checking for ammonia and nitrates is crucial here. To treat this disease, use an antibacterial treatment in a freshwater aquarium, or treat marine and pond fish in a separate isolation tank.
Swim-Bladder Disorder
You will immediately know if your fish suffers from this disorder, as it will be swimming upside down. This can be caused by sudden changes in temperature, or there may be a microbial infection present. Fish suffering from this disorder have difficulty maintaining their position, and will be observed listing or sinking. Swim-bladder can occur spontaneously in healthy livestock, but is common with the fancy goldfish species, such as moors, veiltails and orandas. It's a difficult disorder to deal with as the exact causes of the condition are not well understood. Fish gulp air when they feed at the surface and can become affected. You can try putting the food under the water so the fish have to eat from lower down. If your goldfish or coldwater fish is already affected, try moving it into shallow water (about 5 inches) and slowly increase the water temperature by about 5C. Often fish affected by this condition do not recover. In the case of your fish refusing to eat or being highly stressed, it might be kinder to consider a form of fish euthanasia.
Fish Pox
This is a viral infection, mostly affecting coldwater aquarium and pond fish, especially koi. This condition will often appear and disappear. It is not very infectious and rarely passes to other fish. Although unsightly, it will rarely be fatal. There's no reliable treatment for this condition, but raising the water temperature by 5-10C can sometimes help. Because of the nature of this condition it is not a cause for alarm. However, always check your fish before you buy it, and avoid buying any that look infected.
Fin Rot
Fin rot is a bacterial infection, often occurring in fish that are in a poor condition. You will see ragged or split fins, often displaying a white edge. It often arises with alongside other infections. Bad water quality, fighting, physical damage, rough handling and overcrowding will all predispose fish to this condition. In outdoor ponds, if the water falls below 10C you may see this condition more often. This can usually be cured with and aquarium antibacterial. Sometimes adding a small amount of aquarium salt to a freshwater tank will help to prevent finrot in brackish livebearers such as Mollies and Guppies. Finrot is unlikely to occur if you maintain the correct balance in your tank.
Fish Euthanasia
The aquararist will at some point have to deal with a fish that is too sick to treat, and the issue of suffering arises. Fish do have the same reactions to pain as we do, but they have no ability to express it. Whilst this is a subject many people wish to avoid, in some cases euthanasia is the kindest thing you can do for your fish. Many methods have been proposed over the years, but several of them are far from humane and cause further unnecessary suffering to the fish. This is a situation you want to avoid, and should you feel euthanasia might be necessary, be sure you have considered the following first:
1: Does my fish have a good quality of life?
2: How long has the fish been sick?
3: Have all medical treatments been tested and exhausted?
4: Has the fish responded positively to any treatment?
5: Is the fish eating?
6: Does the fish appear to be suffering?
If you have gone through these questions and are sure that euthanasia is the kindest thing for your fish, there are a couple of methods which I feel are acceptable for ending your fish's suffering.
1: Alcohol. This is considered 100% humane and is very quick. You need to use alcohol as pure as possible, i.e. vodka or tequila. The alcohol needs to be at the same temperature as the water in your tank. Once the fish is introduced to the alcohol, it will become instantly overwhelmed. Alcohol works as an anaesthetic, and will instantly paralyze and anaesthetize the fish causing respiratory failure. This method is recommended for all types of fish.
2: MS-222 (or other veterinarian anaesthetic). This is considered the best method for fish euthanasia. An overdose of anaesthetic given to the fish while in quarantine will cause immediate cardiac arrest. MS-222 is a white powder that must be mixed with water and then added to the fish's water. This method is also considered to be 100% humane.
