Dwarf pencilfish are beautiful and small freshwater fish that many aquarists love to keep in their tanks. It is easy to stock and manage them. However, it’s optimal to know about their profile, optimal tank size, and suitable tank mates, especially shrimps. All of these aspects are discussed in a detailed fashion in this article. By the end of this article, you’ll feel confident in having a nicely-stocked home aquarium.
Content Table
Aquarium Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish is a unique freshwater fish that is popular among aquarists. Their relatively peaceful behavior, small size, aesthetics, and common availability are some reasons for their popularity. Here is a profile of the dwarf Pencilfish.
| Feature | Explanation |
| Scientific name | Nannostomus marginatus |
| Genus | Nannostomus |
| Family | Lebiasinidae |
| Common names | Dwarf pencilfish |
| Marginatus pencilfish | |
| Size | 3.5 cm |
| Shape | Torpedo-like, elongated cylinder body |
| Coloration | A golden hue along the body, with a red line running from the tail to the snout. Subtle color variations, i.e., red, golden, and brown. |
| Population distribution | Guyana |
| Venezuela | |
| Brazil | |
| Colombia | |
| Peru | |
| Suriname | |
| Habitat characteristics | Slow-moving rivers, streams, swamps, and floodplains. Usually present in a dense population. |
| Behavior | Schooling, i.e., living in a group of 8 to 10
Peaceful |
| Aquarium preference | Planted aquarium |
| Feeding | Omnivorous |
| pH | 4 to 7 |
| Temperature | 72-82°F |
| Water hardiness | Soft water |
Communal Dwarf Pencilfish for Shrimp Colonies
You can keep your dwarf pencilfish with shrimps. Beckford’s pencilfish is an example of a species. They are peaceful and compatible with shrimps. However, it is not entirely safe to keep all pencilfish with shrimps. Some pencilfish species love to feast on shrimp, especially baby shrimp.
If you are interested in keeping them in the shrimp tank, introduce the shrimp first. Give them time to establish their colonies. Moreover, the plantation is also a good way to avoid aggression from the pencilfish species. Select some larger shrimps so they can prevent their aggression. However, if you are more concerned about shrimp predation, keep them with other shrimp-safe fish species.
Ideal Dwarf Pencilfish Tank Size
Generally, dwarf Pencilfish require 1.5 gallons per fish. However, they are social and live in groups of 6 or more. The dwarf pencilfish tank size depends on the group size of the fish and the type of plantation. Here is a general tank size recommendation for a small group, i.e., 6 fish, and an ideal group size, i.e., 10 to 12 fish.
| Number of fish | Tank size (gallons) |
| 6 | 15 to 20 |
| 10 to 12 | 25 to 30 |
While selecting the tank, ensure that the tank is more horizontal than vertical. Moreover, fill the space with hiding spots and plantations. Dwarf Pencilfish love to live in such a space.
dwarf pencilfish tank size
Dwarf Pencilfish Stocking Calculation
Generally, dwarf pencilfish require less space, i.e., 1 inch per gallon. With this, an adult will require almost 1.2 gallons of space.
Number of dwarf pencilfish =tank size(gallons)/1.2
Here is a reference table for pencilfish aquarium stock.
| Tank Size (Gal) | Number of Dwarf Pencilfish | Note |
| 10 | 6 | The smallest size to fulfill their schooling behavior |
| 15 | 8 to 10 | Higher stability |
| 20 | 10 to 12 | The ideal group size to observe their natural behavior |
| 30 | 15 to 18 | Large group size
Help to show an active display |
Stocking With Shrimp Colonies
If you want to keep some shrimp colonies in your tank besides the dwarf pencilfish, here are some general considerations and a nicely stocked home aquarium table.
Considerations
- Grow more plants in the tank for shrimp grazing.
- Provide a larger space per pencil fish than a pencil fish-only tank.
- Keep your pencilfish well-fed to avoid shrimp predation.
Stocking Formula
Dwarf pencilfish stocking + Shrimp colony = (tank size -5)/1.5
Where as:
Tank size = (gallons)
5 = gallons for shrimp stocking. This space varies with shrimp size and increases with tank size.
1.5 = gallons are required per dwarf pencilfish
| Tank size | Number of dwarf pencilfish | Shrimps colony size |
| 10 | 5 to 6 | 15 to 30 |
| 15 | 6 to 8 | 30 to 50 |
| 20 | 8 to 10 | 50 to 80 |
| 30 | 12 to 15 | 80 to 120 |
Owning a Nicely Stocked Home Aquarium with Small Fish
Other than aesthetics, owning a small home aquarium is an exciting and healthy hobby. If you’re interested in maintaining a nicely stocked home aquarium with small fish, here’s a general guide. Some aspects are completely species-dependent, i.e., stocking density. Therefore, adjust these factors according to your desired fish species.
nicely stocked home aquariums
Suitable Tank Size
Usually, tank sizes are categorized into three main groups, i.e., small, medium, and large tanks.
| Tank Class | Size (gallons) | Best for |
| Small | 10 to 15 | Nano fish and a small social group |
| Medium | 20 to 40 | Stable
Suitable for relatively larger fish schools |
| Large | 50+ | Flexible
Suitable for having a community fish |
If you are a beginner, it is recommended that you go with the medium-sized tank. It does not require a lot of experience and also handles beginner mistakes.
Stocking Rule
There is no universal rule for fish stocking. It varies depending on several factors, including activity level, tank bio-load, and fish shape. However, the general rule of stocking is 1 inch per gallon. This rule works well for small, slim, and fish under 3 inches.
Refine With Bio-Load and Behavior
Refining is based on various factors, i.e., schooling, activity, and territorial nature. If you plan to keep small schooling fish, keep them in a group of at least six. Active fish require more horizontal open swimming space. The space requirement reaches a peak in the case of territorial fish presence.
Stocking Calculation
If you are planning to stock your fish in a 20-gallon tank. Here is a rough calculation for a community of famous small fish species, i.e., ember tetras, dwarf pencilfish, and pygmy Corydoras.
| Specie | Size (inches) | Group size |
| Ember tetras | 1 | 6 |
| Dwarf pencilfish | 1.2 | 6 |
| Pygmy Corydoras | 1 | 6 |
Factors to Keep the Tank Functioning Properly
- Always use a strong filtration system to handle the entire fish community.
- Grow live plants in the tank. They improve the oxygen level in the tank and help to control waste. Moreover, they provide hiding spots for the fish.
- Weekly, change a certain volume of the tank’s water. The volume depends on the stocked species and their population density.
pencilfish aquarium stock
Gradual Fish Addition
Always quarantine new fish before adding them to the tank. Moreover, don’t stockpile at a time. Stock them gradually in small groups. The sudden introduction of many fish into the tank can cause a spike in ammonia and nitrite levels.
Maintenance
Regularly change the water, keep the filter clean, and monitor the water quality and the fish’s behavior. If you feel any unusual behavior, promptly address the issue, as it leaves less margin for error.
To Conclude
Dwarf pencilfish are common among aquarists due to their small size and peaceful nature. Usually, they grow up to 1.2″. A 20-gallon tank is an ideal setup for stocking, as it can accommodate plants and a community of pencilfish. You can also keep them in a community tank, but be cautious in case of shrimps, as they can eat them. Follow the care, stocking, and other aspects to enjoy a successful home aquarium.
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