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Top 5 Dither Fish to Help Shy or Aggressive Fish

If you have timid or territorial fish in your aquarium, try calming them down with dither fish. Dither fish have outgoing personalities and swim out in the open all the time. Their confident behavior signifies to shy fish that there is no immediate danger and it is safe to come out of hiding. A large group of dither fish also helps to distract and diffuse the hostility from fish bullies so that they can’t single out any one fish. Learn more about the best dither fish that can change the dynamics of your fish tank and give you a more active community aquarium to enjoy.

1. Livebearers

Livebearers are fish that bear live young, and most of the common types at the pet store (e.g., guppies, platies, and mollies) are extremely friendly and colorful. Plus, they reproduce readily, and even their fry will boldly swim everywhere without a care in the world. When skittish fish see these intrepid livebearer babies, they are even more likely to come out.

If you have two angelfish that keep fighting over territory, try adding a bunch of mollies, swordtails, or other larger livebearer to break up the tension. The livebearers will swim all over the place and readily encroach into their personal space. The angelfish cannot keep all the dither fish out of their territory, so the hope is that they will give up trying to defend their boundaries. Yes, the angelfish may eat some of the livebearer fry that wander too close, but this helps keep their population under control so that you are not overrun with babies.

angelfish, platies, and mollies in planted aquarium

Many livebearers have a carefree, easygoing temperament that can help semi-aggressive species like angelfish chill out.

2. Tetras and Rasboras

Both groups of schooling fish are known for their streamlined, torpedo-shaped bodies that make them fast enough to escape even the angriest tank boss. Yes, some tetras and rasboras can be a little on the wary side themselves, especially since most of them are under 3 inches in size. However, they tend to become braver as you increase the size of their school, so get at least 6-12 fish of the same species.

If you want to embolden a shy nano fish, you may want to choose a schooling fish that is also small in size. On the other hand, if you hope to pacify a big and belligerent fish, go with a larger schooling fish that won’t get eaten. Depending on your needs, here are some suggestions categorized by size:

Tetras and rasboras as dither fish - chart


Rummy nose tetras in particular are known to be very tight schooling fish that swim and change direction together like a giant herd. This behavior tends to confuse predators because they have a harder time catching a single fish that is surrounded by a hoard of doppelgangers.

rummy nose tetras in planted fish tank

There’s nothing like seeing a huge group of rummy-nose tetras beautifully swimming back and forth in synchronization.

3. Corydoras

While tetras and rasboras often swim in the middle level of the aquarium, cory catfish stay down low near the floor, constantly scavenging for food out in the open. This makes them a wonderful dither fish for other bottom dwellers like Apistogramma and kribensis cichlids who want to know when it’s safe for their babies to come out and feed. Corydoras are great clean-up crew members that do well in a group of 6 or more of their own species, and there are many kinds to choose from. If you have bigger fish like blood parrots that are capable of swallowing smaller corys, then go for their larger but similar-looking cousins, the Brochis catfish. In fact, you can keep livebearers, tetras, and corys all together in a community tank that is filled with lively dither fish.

albino corydoras on sand substrate

Albino corydoras are one of the most sociable catfish you can find, and they love eating frozen bloodworms, freeze-dried tubifex worms, and sinking pellets.

4. Danios and Rainbowfish

Sometimes medium- to large-sized predators like Jack Dempsey and oscar cichlids can be uncharacteristically shy and prone to hiding. In those cases, you want bigger, super fast schooling fish like giant danios (Devario aequipinnatus) and hill trouts (Barilius spp.) that have a better chance of escaping their jaws. By actively darting around at a million miles an hour and breaking into everyone’s territories, these dither fish give off the message that “I’m a smaller fish, yet I find it safe to freely swim out in the open.” If you have a jumpy bala shark that tends to freak out and ram into walls, you can also try dither fish to help it settle down. Rainbowfish are a very confident and colorful schooling species that calmly swim around and can help pacify other, more nervous species.

Indian Trout Barb (Barilius ardens)

Hill trout are speedy swimmers capable of traveling in fast-flowing streams, so try not to pair them with slower fish who may get outcompeted during mealtimes.

5. Hatchetfish and Pencilfish

What if you have timid fish you want to spawn, but you don’t want the dither fish to eat their babies? Look for top-dwelling fish like hatchetfish and pencilfish. These surface dwellers mostly swim in the upper third of the aquarium and have tiny, upward facing mouths that prefer eating floating foods from above. This is perfect for ram or Apistogramma dwarf cichlids that are guarding their babies down near the substrate. Hatchetfish and pencilfish rarely come down to feed and typically won’t eat fry unless they accidentally swim up top. When you feed the aquarium, the skittish fish will see the dither fish rushing to grab a bite, so then they will feel more comfortable coming out to feed as well.

Diptail brown pencilfish (Nannostomus eques)

Nannostomus eques are known for swimming near the surface at a 45-degree angle, which is why they are sometimes called the diptail or hockeystick pencilfish.

Dither fish can bring out the best behavior in your aquarium by coaxing fish out of hiding, putting the tank bosses at ease, and increasing the activity level overall. If you are looking for some fun fish to try, visit our retail store in Edmunds, Washington or check out our favorite online fish sellers.


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