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How to Worm your Betta

Recognizing the Common Pests Harmful to your Betta Fish






Just like any other creature, your betta fish can suffer from disease and parasites when not properly quarantine when the fish arrives or you are feeding live foods. When fish have parasites they should be considered very contagious. If a fish actually has parasites, it’s highly recommended to separate the fish in question from all the other aquatic life in your fish tank and move to a quarantine tank. Taking the fish out of the aquarium into a portable container is probably always the best way to do so. Otherwise the parasites will most likely spread through the whole fish tank until all fish are infected. Below is a list of seven parasites that are common among tropical fish:


Fish lice — this parasite is very tricky because it is so hard to spot till it has overtaken your fish. This parasite will hide itself by taking on the same color as its host. The host fish will try to get rid of the lice by rubbing its body against stones, plants or along the side of the tank in an effort to try and remove them.

Anchor worms – these parasites are females and have an anchor shaped head, which they use to burrow its way into the flesh of its prey. Once they bury themselves into the fish there may be a little bit of bleeding on the fish where the head has attached itself. You may also be able to see a little worm or tentacle that is white protruding out from the spot where the parasite is attached. Because this parasite’s head is anchor shaped it is difficult to remove, and if pulled out by force may cause the fish to suffer a bleeding wound.

Leeches – Leeches feed on blood and should be removed as soon as possible. Although the leech leaves the fish as soon as it is full, the blood loss might be lethal for delicate tropical fish. Pulling off the parasite by grasping it can cause regurgitation and leave parts of the leech’s jaw attached to the wound, increasing the risk of infection. A better method is to use a fingernail to break the seal of the oral sucker at both ends of the leech. Start off with the small end and then continue with the larger end. The leech will detach its jaws as soon as the sucker’s seal is broken.

Flukes – There are two common types: While skin flukes attach to the skin of your tropical fish and cause swelling, gill flukes will make it hard for the fish to breathe. The gills will turn pink and the fish will probably stay at the water surface where it can breathe easier. These skin flukes can cause localized sores and swelling.

Ichthyophthirius – The so-called ‘ich’ or ‘white spot’ is the most common tropical fish disease, caused by probably the most common freshwater parasite. The typical behavior of an infected fish includes loss of appetite, rubbing itself against objects, flashing and hiding abnormally. Once a fish in your fish tank is infected, quarantine is necessary to prevent the fish from spreading the tropical fish disease to the other tank inhabitants.

Piscinoodinium – The microscopic parasite causes the ‘gold lust disease’, named after the golden patterns that will appear on the scales of your fish. Once your fish are infected, the tropical fish disease can be treated with copper salts, which destroys the parasites in your water.

Hexamita – these parasites are also known as hole in the head disease. They are basically internal parasites. These are harmful to your fish when he is weak because of age, stress or bad water conditions.


The best way to avoid outbreaks is to always quarantine new fish and treat them as if they are infected. Schedule worming on all fish fed live foods at least 2 times a year and do regular water changes.


How to use Metronidazole and Dosage

Metronidazole or MNZ is the most popular and really the most effective antiprotozoal medication in aquarium and ornamental fish industry which is used to treat a vast variety and range of both internal and external protozoan infections and parasites (not worms) in bettas and other tropical fish. Other than a strong and very reliable antiprotozoal drug, metronidazole is also a very good antibiotic medication that can treat Anaerobic bacterial infections as well as most other medications. Other brand names of the same drug are Flagyl, Metrogel, Noritate, and MetroCream tropicalfix and several other names. However, API is more or less the most common to be found brand names in the US market.


How to use Metronidazole to treat betta Fish

Bettas are like most other scaled tropical fish when it comes to treatment. But, when it comes to betta fish, the metronidazole products play a very important role in all quarantining new fish, prevention, and treatment processes and when used at the same time as Kanaplex (kanamycin sulfate (32%) it is pretty much unbeatable in a quarantine treatment now days. MNZ is mostly used now days to treat different kinds of flagellates and Internal protozoan parasites such as hexamita, external protozoan infections like Spironucleus which causes hole in the head & head and lateral line disease, Anaerobic bacterial infections, digestive and intestinal disorders, and etc.


Dosage & Administration

Now before I go into dosage you need to understand all fish are not the same. The second you fish shows signs of stress you will need to stop treatment and lower the dose and change 505 of the water A.S.A.P. With that being said the dosage, administration, and frequency, I would have to say that It really depends on circumstances and can vary case by case. A strange and interesting fact is, there is no consensus among researchers, breeders, hobbyists, ornamental fish distributors, farms, and etc. For this reason, there are so many different doses and administration routes for metronidazole it can make your head spin. In the next paragraph, you will learn how to treat betta’s with metronidazole and do it with some safety and without much of an over dose issue.


Metronidazole Dosage, How to Use MNZ for Betta Fish

So, here we are! This is what you have been waiting for and I am glad you have read this far. According to what I and others have read, learned, and experienced at our farm over the past 30+ years and also my personal research opinion, the standard and the most effective dosage for the metronidazole with bettas is 200 mg per 10 gallons of water every other day for 5 days with at least 50% water change before each daily dose. Keep in mind that at least a minimum of 3 doses is always necessary to eliminate the newly hatched larvae of the parasites and that is because the eggs from parasites are not affected by Noritate; So that, although most of the live parasites will die rapidly right after the first dose of the medicine, the parasites eggs will be hatched couple of hours later. This type of medication breaks they life cycle on adults and larval forms and not the eggs. Make sure to keep that in you mind.


Medicated Food & Doses

Metronidazole also can be used in fish food to improve the treatment effects and we suggest it. Just soak a little food in some powder mixed with clean water and feed as the main food during quarantine.  However, not in all cases the internally sick fish will eat.  Having said that, treating betta fish with metronidazole is being done by different and sometimes weird doses some of them which are much stronger than betta liver can handle and is why we wrote this.

NOTE: Human Metronidazole powders and tablets are not so water soluble and without using proper excipients and/or solvents, it is very unlikely that the drug will be effective in tropical fish at all, unless it is used in a medicated food. It is highly recommended to use an aquarium/fish medicine as they are very water soluble. Fish medications such as those by API and Seachem MetroPlex™ are some of the best fish medications with active ingredient of Metronidazole.


Below are some alternatives that can be used with good results also, 


Liquid PraziPro™ is a ready-to-use, liquid concentrate that was developed to offer the hobbyist an effective way to control unwanted parasites in their pond, freshwater or marine aquarium. Extremely safe and super effective this revolutionary product offer you rapid control yet will not negatively impact your biological filtration. Send those unwanted visitors on their way, try Liquid PraziPro™ today! 4 oz. treats 480 gallons




Fenbendazole is used as a worming agent in tropical fish and is extremely effective in both fresh and salt water environments. It has replaced levamisole (Discomed) since the fish do not build a resistance to it. Fish Bendazole works so quickly that you will usually see worms protruding from infected fish within an hour!




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