Top 10 for the 10-Gallon Tank

Author: Neale Monks

The author, a veteran in the fishkeeping hobby, details 10 species that make excellent inhabitants for the popular—but seldom properly stocked—10-gallon tank.

A Tank for Beginners

A 10-gallon tank would seem to be an ideal first step into the fishkeeping hobby, as they are inexpensive, not too big, and easy to carry home. Fish tanks of this size are especially popular at Christmas, when people are looking for fun but educational gifts to give (especially for children).

But what sort of fish should you put in one of these tanks? One obvious factor to consider is the adult size of the fish. Angelfish and plecos, for example, may be sold at an appealingly small size, but as adults, they are simply too large for a 10-gallon tank. You also need to consider behavior. Fish such as danios that need a lot of swimming space won’t be happy in 10 gallons. Similarly, territorial or aggressive fish like dwarf pufferfish will need to be left out as well.

Easy Care Fish

What you want are small, relatively inactive, and definitely non-aggressive fish. All the species listed below will work in a 10-gallon tank, either alone or as part of a community. They will also adapt to a range of water conditions, and none of these require any specialist care, such as the use of live foods. This should make them viable choices even for relatively inexperienced aquarists.

How Many Fish Will Fit?

The next question is how many small fish can you add to a 10-gallon tank? Initially, aim for around one small fish per gallon of water, adding them in small groups every couple of weeks. Once the aquarium is mature and your skills are honed, you should be able to keep two neon-tetra-size fish per gallon.

Filtration

This does rather depend on your fishkeeping skills and the quality of the filter. Look for a filter with a turnover of 40 to 60 gallons per hour, and perform 50-percent water changes every week. A nitrite test kit is also very useful, especially while your aquarium is being established. Use this to check the water quality at least once a week.

Small fish tend to be sensitive to poor water quality, so if you can, mature the aquarium using a fishless cycling method. Your retailer should have a variety of products that will help you do this. Alternatively, take some mature filter media from an established filter and put it into the filter of your new aquarium. This will jump-start the biological filtration process, allowing you to add your first batch of fish right away.

Top 10 Fish for 10-Gallon Tanks

And so, with the above in mind, here are my picks for 10 livestock choices that can be properly kept happy and healthy in a well-maintained 10-gallon aquarium.

#1: Dwarf Corydoras

Most small Corydoras species can be wedged into a 10-gallon tank, but a couple of dwarf species really stand out as being ideal choices. The first is Corydoras habrosus, which gets to about 1½ inches in length. They are busy little creatures and are a joy to watch. Like other Corydoras, they are schooling fish, so keep them in a group of six or more.

Corydoras hastatus is even smaller, barely an inch long when fully grown, but what really sets it apart from most other corys is that it is a mid-water fish. If kept with larger fish, they tend to stay out of sight, hidden among the plants; but if their tankmates are of similar size, these adorable catfish will flutter all over the tank, often hovering in the current and twitching their fins and whiskers like strange little hummingbirds!

Corydoras pygmaeus is similar to C. hastatus, though less widely traded, and can be kept in just the same way.

#2: Neons, Cardinals, and Glowlights

Here are three fish guaranteed to catch the eye. Neon tetras Paracheirodon innesi are relatively inactive animals. This makes them a better choice for the small aquarium than similarly sized danios or minnows. Neons mostly like to hang out under a bushy plant and just wait for some food to come drifting by.

Cardinal tetras Paracheirodon axelrodi are similar to neons in shape and color, though a bit larger. Basic care is similar, although cardinals prefer slightly warmer water than neons, so it’s a good idea to choose one or the other depending on what your other fish prefer. For neons, 68° to 78°F suits them well, while cardinals prefer 74° to 80°F—or you could just keep both at a nice happy medium, around 75° to 77°F.

Glowlight tetras Hemigrammus erythrozonus are slightly larger than cardinals. They are basically transparent, but with a lovely copper-colored band running along the midline of the fish from nose to tail. Glowlights really earn their keep in tanks with a dark substrate and lots of plants. Adding a bit of blackwater extract to the water makes them look even better. In fact, neons and cardinals also look their best in dark tanks that mimic the blackwater streams of their natural habitats.

#3: Sparkling Gouramis

The sparkling gourami Trichopsis pumila is a jewel that lives up to its name, with brilliant blue spangles on a pinkish-brown body. A mere 1½ inches or so in length, sparkling gouramis are perfectly suited to a small, thickly planted aquarium where they will swim about at all levels but mostly close to the top. They can be quite shy, but if kept in a peaceful tank away from nippy or aggressive fish, they will become much more outgoing.

Sparkling gouramis aren’t particularly territorial, and a 10-gallon tank can easily house four or five specimens without problems, especially if there are lots of hiding places. When kept in groups they are surprisingly noisy as well, making croaking and purring sounds that are presumably used as threats or to attract mates. Definitely something to listen for!

Alternatives to sparkling gouramis include honey gouramis Trichogaster chuna and female Siamese fighting fish Betta splendens. Dwarf gouramis Colisa lalia are best avoided, though. The males tend to be rather aggressive, and in recent years, farmed fish have been plagued with a viral infection that causes lethargy, body sores, and eventually death.

#4: Kuhli Loaches

A number of different species of Pangio are sold as kuhli loaches, though the most commonly seen is probably Pangio kuhlii, a worm-like fish that is 3 to 4 inches long, with a pinkish-orange body ringed with thick chocolate-brown bands. Their natural habitat is the leaf litter at the bottom of streams, where their coloring helps them to hide from predators. If such discretion doesn’t work, these loaches are armed with sharp, erectile spines in front of their eyes that make them an unpleasant mouthful.

Because kuhli loaches are small and hardly swim around at all, they can be excellent fish for the small aquarium. They usually slither around the bottom of the tank looking for morsels of food. Unlike most other loaches, kuhli loaches are completely peaceful and need the company of their own kind. Keep them in groups of four or more for best results. Kuhli loaches make excellent community fish, and will happily feed at night on things like catfish pellets and bloodworms.

Mature females are remarkably robust and quite a bit longer than the males, but for whatever reason, this species very rarely breeds in aquaria. They are otherwise easy to keep, except for a tendency to find their way out of uncovered tanks.

#5: Dwarf Lamprologus

The small shell-dwelling cichlids of Lake Tanganyika can make excellent additions to the community tank. While territorial, they tend to ignore fishes in the middle and upper levels of the tank. Since they need hard, alkaline water there’s no point keeping them in a soft-water community, but combined with surface-dwelling hard-water fish like the least killifish (see #7) or Endler’s guppy, these dwarf lamps are a nice way to get into Tanganyikan cichlids.

A good species for beginners is Neolamprologus brevis. Males are a mere 1½ inches when fully grown, and females even smaller. Both are pinkish-brown with electric-blue markings on the face and flanks. A 10-gallon tank will easily house a pair of these fish. Although the pair will share the same shell, it is a good idea to provide them with a variety of shells so that they can choose their own home. Clean apple-snail shells are ideal, and can be picked up from tropical fish shops easily enough; but another good type of shell is the type sold in gourmet food stores for serving escargot. Once settled in, the pair will spawn inside the shell with both parents guarding the eggs and fry.

There are quite a few shell-dwellers that turn up less frequently, such as Lamprologus ocellatus. Most of these tend to form harems rather than pairs; that is, the male needs to be kept with a group of two or more females. Each fish needs its own shell, and the male will mate with all the females, and will show little interest in guarding the eggs or fry. Basic care is otherwise similar to N. brevis.

#6: Pencilfish

Inexperienced aquarists are often advised to avoid the pencilfish of the genus Nannostomus. While they are certainly pretty and peaceful, they are sensitive to water chemistry and often fail to adapt to busy community aquaria. The one notable exception is the golden pencilfish Nannostomus beckfordi.

The golden pencilfish is a small, slender fish that gets to about 2 inches in length. Its basic color is golden green with several blue-black bands running from nose to tail and brilliant red markings on the anal and tail fins. Golden pencilfish need to be kept in groups of six or more specimens. Males are distinctly territorial though, and will spend a lot of time chasing one another. No harm is ever done, and their boisterous antics really only add to their charm.

Because pencilfish move about in a slow, rather deliberate sort of way, they work well in small planted tanks. Golden pencilfish are adaptable and will eat all sorts of foods, including flakes, something that cannot be said for most other pencilfish. Also unlike most other pencilfish, golden pencilfish will adapt successfully to hard, alkaline water conditions. All in all, they make an excellent alternative to the more commonly kept characins.

#7: Least Killifish

The least killifish is, despite its name, a livebearer and not a killifish at all. It is one of the smallest fish known to science, and a native of the southern United States. Males are slightly less than an inch in length, females about 1½ inches. Both sexes are rather similar in looks, being semi-transparent silvery green with a dark band running from behind the eye to the base of the tail. There are distinctive black blotches on the anal and dorsal fins.

The least killifish is not a difficult fish to keep, despite its miniscule size. It prefers hard and alkaline fresh water, but will also do well in slightly brackish systems. As a subtropical fish, it doesn’t need a great deal of warmth, and could be kept in an unheated tank in the warmer parts of the world. Feeding this fish couldn’t be simpler: flake, algae, and small live foods such as Daphnia are all readily taken. The least killifish appreciates a thickly planted aquarium. Floating plants are especially useful as cover for newborn fish, which are tiny and at severe risk of being eaten by any carnivorous tankmates.

#8: Celestichthys margaritatus

Initially known as the galaxy rasbora Microrasbora sp. “galaxy” but now properly called the celestial pearl danio Celestichthys margaritatus, this lovely fish was discovered in Burma in 2006, and quickly became a hit among fishkeepers around the world. Because wild populations turned out to be small and vulnerable to extinction, the Burmese government has restricted exports of wild fish, but C. margaritatus has proven to be easy to breed, and farmed fish are now widely available.

C. margaritatus has a blue-green body covered with small cream-colored spots. The fins are marked with red and black stripes. Males have brighter colors than females, but otherwise the two sexes are similar. They are shy, and need to be kept as a group in a well-planted aquarium.

C. margaritatus is rather surprising in its needs; it’s a fish that prefers cool, hard, slightly alkaline water rather than the warm, soft, acidic water we tend to associate with Southeast Asian fish. Its tiny adult size of well under an inch makes it a viable schooling fish for the small aquarium despite being quite active.

#9: Cherry Shrimp

Okay, small freshwater shrimps in the genera Neocaridina and Caridina obviously aren’t fish! But they do bring a quirky splash of color to the small aquarium, and they can perform a useful role as combination algae eater and scavenger. Some are red and are called by such names as cherry and crystal red shrimps. These are small (around an inch long) and work extremely well alongside fish of similar size. They are sociable and best kept in groups. Aside from algae, they will eat scraps of fish food as well as decaying organic detritus and various microorganisms. They seem to do best in moderately hard water with a neutral to slightly alkaline pH.

In the solid red species, juveniles and mature males are transparent with a few red markings, whereas mature females are red all over. Under good conditions, cherry shrimps breed freely. Females will carry bunches of eggs under their abdomen for about two weeks, at which point the eggs hatch and a few dozen miniature shrimps will emerge. In a planted tank with lots of hiding places, at least a few shrimps will survive to maturity. A big lump of Java moss seems to suit cherry shrimps perfectly. Not only does it give the juveniles cover and the adults somewhere to molt safely, the moss also traps algae and small particles of food. The shrimps will congregate on the moss and graze away contentedly.

Their growth rate is surprisingly rapid, with shrimps reaching maturity after only a couple of months. Look after your cherry shrimps properly, and you’ll soon have quite a colony to share with your friends.

#10: Nerite Snails

Obviously these aren’t fish either, but nerites do answer the question of what snail to add to a tank without the risk of them taking over. Nerites hardly ever breed under aquarium conditions for reasons not fully understood. Better still, nerites are excellent algae eaters, and they never harm aquarium plants. Best of all, they come in a wide variety of shapes and colors.

Nerites live in clean, fast-flowing streams and rivers, and they do not tolerate pollution in the wild or in aquaria. This can make them a bit delicate in immature tanks. But in a stable aquarium they do well enough, though few species seem to live for more than a year or two.

One problem with nerites is that some of the species traded are brackish-water varieties, and these will not do well in freshwater aquaria. The most common of these is the olive nerite Vittina usnea, also known as Neritina reclivata. Among the true freshwater nerites are various species of Clithon, Neritina and Vittina, often sold as “batman snails,” “spiny snails,” “zebra snails,” and other extravagant and not altogether helpful common names. None of the nerites get very large—most measure about half an inch or so across the shell.

Envoi

Thickly planted with small species of Cryptocoryne, Anubias, and Java moss (all of which do well under moderate lighting), the 10-gallon tank can be a wonderful home for a variety of lovely fishes and invertebrates. Just go slowly, keep on top of water quality, avoid overstocking and overfeeding, and most of all, enjoy!

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