Are Neon Tetras Right for My Aquarium?

The Neon Tetra (Paracheirodon innesi), is a peaceful fish that is ideal for community aquariums. These schooling fish grow to be 4 cm, and tolerate temperatures from 20-26º C. Neons can tolerate ph values from 6-8, but prefer a mid to lower the value of 6.5-7. Originally from South America, most Neon Tetras available for sale are now commercially bred.

What do they eat?

Neon Tetras are not picky about what they eat. Quality tropical flake food is good but may have to be crushed up with your fingers while feeding. Frozen baby brine shrimp once in a while is a good idea, too.


It will take a hobbyist some practice to tell the difference between male and female Neon Tetras, as differences between the sexes are not easy to notice. The female is more robust with a rounder belly, with the males being more slender. The iridescent blue line that gives the Neon its name usually does not shine as bright on the female and is slightly bent compared to that of the male.

What Makes a Neon Tetra Glow?

Neon Tetras, and other fish with iridescent colors, glow because of cells called iridophores. These cells contain guanine crystals that reflect light and enhance certain colors of light when viewed at different angles. Iridophores expand when there is a lot of light shining on them (such as when Neons emit a bright blue color), and contract in the dark (such as the pale green color of Neons Tetras first thing in the morning).

Since Neon Tetras are often found in black water regions, or water that it very dark, iridophores are thought to serve as markers to let other Neons know where the rest of their school is. Basically, the “neon” quality of the Neon Tetra acts just like a lit-up sign, saying, “Hey, I’m over here, lets go for a swim!”

What Tank Size Does it Need?

Since Neons are small in size, they are suitable for 2 gallon desk top aquariums, to the largest of tanks. Caution should be used in bigger tanks with powerful filters, as Neons sometimes get sucked into the intake tubes. Using a piece of sponge to cover the tube will prevent this.

Since Neon Tetras can survive in a wide range of temperatures, they can usually survive in an unheated aquarium kept at room temperature. In cooler conditions, though, the colors of the Neon Tetra tend to fade.

Even though Neons are suitable for small tanks, they should not be kept in bowls. These fish originate in the fast moving, clean water of rivers. Without a filter, Neon Tetras won’t last long. The only fish suitable for bowls are Bettas.

What Fish Can be Kept With Neon Tetras?

Though these Tetras are peaceful, their small size puts them at a disadvantage. Any fish that can get another into its mouth probably will (such as angelfish), so keep Neons with fish that get no bigger than 7 cm. Fish such as Glowlight, Rummy-nose, and Red Eye Tetras, as well as Harlequin Rasboras and Cory Cats make excellent tank mates.

Aquarium Decorations

Tetras appreciate a well planted aquarium. To keep aquarium plants alive and healthy, fluorescent light is needed, which many small aquariums do not have. In this case, silk and/or plastic plants make an adequate substitute.

Driftwood also makes a great addition to a fish tank housing Neons. It will buffer the water, creating the soft conditions they enjoy. Driftwood also provides shade in the aquarium, and Neon Tetras do enjoy darker areas.


2 Responses

  1. Hi!

    I have a relatively new 10-gal setup (my first in about 30 years!), and I’ve been very careful about getting it cycling before adding fish. The tank gets a 20% change every week, and I always check chemistry just before the change. The water is consistently pH 7.4-7.6, and NH4, NO2, and NO3 are 0s. I ensure chlorine/chloramines are first removed from the tap water before I use it, and it’s heated to temp (approx 77) and aerated (to drive down pH as much as possible) before using. I started with a few Panda Corys and Pristella Tetras, and they’ve done great for over a month. Then I added 4 neons from my LFS. I lost one the first day, but the other 3 seemed to be fine, so I chalked it up to chance or accident. However, in the last week, I’ve lost 4 more (this includes replacements to the originals). In all cases, their behavior initially appears absolutely normal – eating, swimming, schooling, etc. No overaggression by other fish that I’ve seen. Then, I’ll notice that one neon is swimming listlessly and keeling to the side, and it’s dead by the next day. No visible indication of disease. I’m at a loss, except to think that the pH is perhaps a bit high. No problems at all with the Pristellas or Corys. Any suggestions would be helpful. Thanks for your time.

    1. I have been told by other hobbyists that neon tetras tend to prefer a lower pH and softer water, so either of those things may be your issue. I’ve heard of people using Indian almond leaves or even driftwood with most of the tannins still in it to help lower the pH. That would mean you would have “tea” water, which many people don’t find all that attractive, but it might be just what you need.

      I would assume that you already know this but just in case; if you do choose to use tannins to lower the pH, don’t use carbon filtration! It would just remove all the tannins from the water.

      It may also be a matter of tank stocking or environment. 10 gallons really isn’t a lot of room for as many fish as you’re putting in. Especially if your tank isn’t very heavily planted or decorated, the fish may just be too stressed or might not be able to handle the water quality that develops from overstocking a tank.

      You might also review your water tests just in case it’s actually an issue of water quality. Don’t rely on strips (they’re not very reliable). If you are using a liquid test kid, double check that you’re doing the nitrate test correctly. If your tank is cycled, unless is it very, VERY heavily planted (and in a 10 gallon with such a large stock I doubt plants would make enough of a difference anyway), you should have some nitrates by the end of the week, especially if your tank is so heavily populated. If you’re using API’s test kit, I know there’s some discrepancy with how to use the test since the ingredients in Nitrate bottle #2 tend to separate. Generally the solution to that is to shake the bottle really, really well first, then shake the test tube for at least a minute in the end. If it turns out that something was wrong with your water tests and you actually do have a lot of nitrate in the water each week, you might just need to do bigger or more frequent water changes.

      Good luck!

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