Neon tetras are a popular nano fish known for their beautiful, red and blue stripes, but sometimes they get a bad reputation for being a “sensitive” fish that is prone to dying. In our experience, these tetras are just as hardy as other danios and rasboras, but there are several factors that may weaken their immunity and make them more inclined to catch illnesses. Let’s discuss why neon tetras get sick, what is neon tetra disease, and how to prevent it.
The first reason why neon tetras may seem sickly is because they are kept in large numbers. Fish farms know they are always in demand and therefore breed them in massive quantities. Wholesalers procure thousands of them at a time, large batches get sent to your local pet store, and then the retail employee mixes the latest shipment of tetras with an existing group that hasn’t sold yet. When you keep tons of fish together, there is an increased risk that at least one of them is sick and will pass on their disease to others.
Neon tetras also tend to be underfed at the various facilities they are kept in. The fish farms, wholesalers, and pet stores all want to spend the least amount of food and time with the fish as possible so that they can stay profitable. A whole tank of 100 tetras may only get a few pinches of fish flakes, which means not every fish gets a bite. For most fish, this practice works okay in the short term, but for neon tetras being kept in high-stress, overcrowded environments, you start to see diseases like ich, fungal infections, or even neon tetra disease.
Neon tetras are frequently kept in large numbers with little food and suboptimal conditions.
Finally, many beginners tend to buy neon tetras because they are colorful and cheap. Oftentimes, they don’t spend a lot of time looking up the care requirements and may buy a large bag of them to put in a tiny aquarium with poor water quality and aggressive tank mates. If neon tetras were pricier and cost $10 each, people would likely be more careful and do research on proper husbandry before taking them home. That’s why we believe that neon tetras are not necessarily more sensitive than other fish; they just get kept in potentially worse conditions throughout the supply chain.
If possible, try to buy the biggest neon tetras you can. Sometimes they are sold as jumbo, XL, or large neon tetras. While they usually cost more, it’s well-worth the price because fish farms must feed more food to these tetras in order to raise them to a certain size. At Aquarium Co-Op, we try to order the bigger, full-grown neon tetras, put them in quarantine, treatwith preventative medications, and feed them well. These best practices help our customers be more successful with their neon tetras and ultimately more satisfied with our store.
After you take your neon tetras home, help them to reach a healthy weight by feeding a wide variety of tiny foods. Frozen bloodworms may be too large for little juveniles, so instead try baby brine shrimp, daphnia, cyclops, crushed up flakes, and micro pellets. Also, they like to eat while the food is slowly sinking in the middle of the water (rather than off the ground), so give them several small meals throughout the day for maximum effectiveness.
NTD is one of the most misdiagnosed diseases in the hobby. Just because a neon tetra is sick doesn’t automatically mean that it has neon tetra disease. If your tetra has white spots, it probably has ich. If your tetra has a white patch, it could be symptom of NTD, but it could also be a symptom of many other illnesses. NTD is fairly rare, so the white patch is more likely caused by a common bacterial or fungal infection. We recommend using the quarantine medication trio (which treats bacteria, fungus, and parasites) and building up the fish’s immunity with fresh foods and good care. If the disease still doesn’t go away and is steadily knocking out fish over time, then you could have a case of NTD.
This neon tetra has a tiny white patch on its body that is hard to accurately diagnose without professional lab equipment and proper training.
NTD is caused by a mycobacterium that is sometimes misidentified as fish tuberculosis. It thrives in environments with warm water, low dissolved oxygen, low pH, and organically rich environments. Many of these conditions often exist in tanks where neon tetras are kept. In her publication on Mycobacterial Infections of Fish, Dr. Ruth Francis-Floyd states, “Poor husbandry, chronic stress, or anything else that impairs the immune function of the fish will increase the likelihood that infection will develop.”
Unfortunately, NTD currently cannot be cured and is highly contagious. Therefore, the best course of action is prevention and minimizing its spread. Quarantine all new fish in a separate container for several weeks to observe them for health issues and prevent exposure to your existing animals. Use the quarantine tank to also help them recover after their stressful journey from the fish farm. Keep the water a little cooler at 74-76°F (23-24°C), don’t include any territorial tank mates, add an air stone or sponge filter for increased oxygenation, and feed a good mixture of healthy foods. If you spot a sick neon tetra that likely has NTD and does not respond to your ministrations, you may need to consider euthanizing it to save the rest of the school.
A curved spine or twisted body is often touted as a symptom of NTD, but we believe malformed neon tetras tend to be a breeding issue. Fish farms produce tons of nano fish and don’t have time to sift through them to take out the ones with bent backs. In fact, instead of individually counting them, they weigh the neon tetras to approximate their numbers for shipping. It’s only once they land at the fish store that employees might have time to scoop out the defective fish because they don’t want the shop to look bad. If you buy neon tetras when they are really small, it can be hard to tell which ones have bad spines, and the problem won’t be apparent until they get older and bigger.
A crooked spine is not a usual symptom of mycobacterium and instead may be caused by a birth defect or injury.
Bottom line: don’t be afraid of neon tetras or neon tetra disease. Over the years, our fish store has seen thousands and thousands of fish, and while we have lost a few fish to mycobacterium, we have never seen NTD run rampant or wipe out an entire tank of neon tetras. They are just as resilient as other schooling nano fish, and we believe they’re one of the best fish you can get for a beautiful display aquarium. Check out our preferred online fish vendors to get your own neon tetras today:
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