5 Best Fish for Beginners: Hardy and Easy-to-Care-For Species
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Setting up your first aquarium can seem simple: choose a tank, add some decorations, fill it with water, and pick a fish you like. But keeping fish healthy involves more than choosing a beautiful species.
Every fish has specific needs for space, temperature, water chemistry, diet, and social behavior. The good news is that several hardy freshwater species can be excellent choices for beginners when their basic requirements are met.
In this guide, we'll look at five popular freshwater fish, starting with species that are relatively easy to keep and moving toward those that require a little more attention.
Important: Hardy does not mean indestructible. Every fish needs clean, stable water, appropriate space, proper filtration, and regular maintenance.
1. Platy — A Colorful and Hardy Choice
Common name: Platy
Scientific name: Xiphophorus maculatus
Adult size: approximately 2–2.5 inches (5–6 cm)
Tank size: around 14 gallons (54 liters) or larger
Temperature: 68–79°F (20–26°C)
pH: around 7.0–8.2
Diet: Omnivorous
Difficulty: Easy
If you're looking for a fish that combines color, personality, and hardiness, the Platy is a strong option for a beginner aquarium.
Platies come in many colors and patterns and are livebearers, meaning females give birth to free-swimming fry rather than laying eggs. They generally do best in neutral to alkaline, relatively hard water, so they are particularly suitable for aquariums with those conditions.
Aquarium and water
A tank of around 14 gallons (54 liters) or larger can be a suitable starting point for a small group. The aquarium should have an appropriately sized filter, good water circulation, safe substrate, adequate lighting, and stable, conditioned water.
A separate air pump is not necessarily required if the filter provides enough surface movement for good oxygen exchange.
Decor and feeding
Live plants such as Anubias and Java moss can provide shelter and make the aquarium more natural. Smooth rocks and aquarium-safe driftwood can also be used.
Platies are omnivores and generally accept quality flakes or small pellets. Offer small portions and avoid leaving uneaten food in the aquarium, as excess food can contribute to poor water quality.
One thing beginners should know is that Platies can reproduce quickly. Keeping males and females together can result in fry appearing in the aquarium.
Availability: Platies are widely available in aquarium stores.
2. Corydoras — Social Bottom-Dwelling Fish
Common name: Corydoras, Cory catfish
Scientific name: Corydoras spp.
Adult size: varies by species; Corydoras paleatus can reach around 2.8 inches (7 cm)
Tank size: around 18 gallons (70 liters) for Corydoras paleatus
Temperature: approximately 72–79°F (22–26°C) for C. paleatus
pH: approximately 6.0–7.0
Diet: Omnivorous
Difficulty: Easy when properly cared for
Corydoras are small bottom-dwelling fish known for their active and curious behavior. They are also social fish, which means they should be kept in groups rather than alone.
The number needed depends on the species, but keeping a group of the same species allows them to display more natural social behavior.
Are Corydoras really tank cleaners?
Corydoras may eat food that reaches the bottom, but they are not a replacement for aquarium maintenance. They still need to be fed properly with suitable sinking foods.
Substrate, water, and filtration
A fine, smooth substrate such as aquarium-safe sand is particularly suitable because Corydoras spend much of their time searching through the substrate with the sensitive barbels around their mouths.
The aquarium should have clean, stable, well-oxygenated water and appropriate filtration. An additional air pump can be useful when extra aeration is needed, but it is not automatically necessary when the filter already provides sufficient surface movement.
Availability: Corydoras are popular and commonly available at aquarium stores.
3. Molly — Hardy, Active, and Adaptable
Common name: Molly
Scientific name: Poecilia sphenops
Adult size: around 3 inches (8 cm) for P. sphenops
Tank size: around 21 gallons (80 liters) or larger for a small group
Temperature: approximately 70–82°F (21–28°C)
pH: approximately 7.0–8.5
Diet: Omnivorous
Difficulty: Easy when kept in suitable water
Mollies are active, hardy fish available in many colors and body shapes. However, their water requirements are important to understand before choosing them.
They generally prefer harder, more alkaline water, so they may not be the best match for an aquarium with naturally soft, acidic water.
Aquarium and water
For Poecilia sphenops, a pH around 7.0–8.5 is commonly recommended, together with relatively hard water.
Seriously Fish recommends approximately 81 liters (21 gallons) for this species, with a footprint around 90 × 30 cm. Mollies are active swimmers, so aquarium length is also important.
As with other fish, keeping water stable is more important than constantly trying to adjust it toward a single "perfect" number.
Feeding and reproduction
Mollies are omnivorous but have a strong preference for plant matter. A quality omnivore food can be supplemented with suitable vegetable-based foods.
They are also livebearers and can reproduce easily. If males and females are kept together, be prepared for the possibility of fry.
Availability: Mollies are widely available in aquarium stores.
4. Neon Tetra — Small, Colorful, and More Sensitive to New Aquariums
Common name: Neon Tetra
Scientific name: Paracheirodon innesi
Adult size: approximately 1.2–1.6 inches (3–4 cm)
Tank size: around 14 gallons (54 liters) or larger
Group: ideally 8–10 or more
Temperature: approximately 68–79°F (20–26°C)
Water: naturally associated with soft, acidic water
Diet: Omnivorous
Difficulty: Easier once the aquarium is mature and stable
Neon Tetras look like an easy choice for beginners: they are small, colorful, widely available, and relatively easy to find. However, they should not be added to a brand-new aquarium.
Neon Tetras need a mature, cycled aquarium
These fish do best in a fully cycled and biologically stable aquarium. A newly set-up tank needs time for beneficial bacteria to become established and process toxic ammonia and nitrite. Regular water testing is an important part of making sure the aquarium is ready for fish.
Do Neon Tetras need a school?
Yes. Neon Tetras are schooling fish, and Seriously Fish recommends keeping them in groups of at least 8–10 individuals so they can display more natural social behavior.
A small aquarium containing only two or three Neon Tetras does not provide the social environment these fish need.
Water and aquarium setup
In the wild, Paracheirodon innesi is associated with soft, acidic water. In a home aquarium, stable conditions are especially important, so sudden changes in water chemistry should be avoided.
Neon Tetras look particularly striking in planted aquariums. Plants, driftwood, and shaded areas can provide cover while making their blue and red coloration stand out.
Feeding and filtration
Because they are small fish, Neon Tetras need appropriately sized food. High-quality micro pellets and flakes can work well, with suitable frozen or live foods such as baby brine shrimp or daphnia offered occasionally.
A proper filter is essential for maintaining water quality. An air pump can provide additional aeration when necessary, but it does not replace biological filtration.
Availability: Neon Tetras are widely available in the aquarium trade.
5. Betta — Beautiful, Popular, and Often Misunderstood
Common name: Betta, Siamese Fighting Fish
Scientific name: Betta splendens
Adult size: approximately 2.8 inches (7 cm)
Tank size: at least 5 gallons (20 liters) for a single male
Temperature: approximately 75–82°F (24–28°C)
pH: approximately 6.0–8.0
Diet: Primarily carnivorous/insectivorous
Difficulty: Easy with a properly set-up aquarium
The Betta is one of the most familiar aquarium fish, but it is also one of the species most affected by misconceptions about aquarium care.
Just because Bettas are often sold in small containers does not mean they should live in them. OATA recommends a tank of at least 20 liters (5 gallons) for a single male, together with filtration, appropriate heating, safe decorations, and gentle water movement.
Temperature and filtration
Bettas are tropical fish, so a stable temperature of approximately 24–28°C (75–82°F) is appropriate. If room temperature is not consistently warm enough, a thermostatic heater may be necessary.
Bettas also benefit from filtration, but the water flow should be gentle. Fish with long fins can find strong currents tiring, making a gentle-flow filter or sponge filter a useful option.
Feeding
Bettas have a primarily carnivorous and insect-based diet. A quality Betta-specific pellet can form the basis of their diet, with suitable foods offered occasionally for variety.
Overfeeding should be avoided because excess food can contribute to health problems and poor water quality.
What can cause problems for a Betta?
Poor water quality, an uncycled aquarium, unsuitable temperatures, overfeeding, strong water flow, inadequate maintenance, and an inappropriate tank setup can all cause serious problems.
There are also several other common mistakes involving water, feeding, decorations, and tank mates. We cover those in much more detail in our dedicated Betta guide:
Why Do Bettas Die So Young? 7 Common Betta Care Mistakes
Availability: Bettas are widely available in aquarium stores and pet shops.
What About Those Brightly Colored Aquarium Rocks?
Brightly colored gravel and decorative stones are common in aquarium stores. They can make an aquarium look playful and colorful, but not every decorative material is suitable for permanent use underwater.
The issue is not simply that a material is colorful. Some aquarium substrates are specifically manufactured and treated for submerged use, while other decorative materials may have coatings or finishes that were never designed to remain underwater.
For that reason, choose substrate and decorations specifically sold for aquarium use and check that they are intended to remain submerged.
What to avoid
- Unidentified decorative rocks or gravel
- Craft rocks or stones painted for decoration
- Materials with chipped or peeling coatings
- Metal objects
- Decorations with sharp edges
- Materials that may release residues into the water
- Objects that were never intended for aquarium use
Safer choices
- Aquarium-safe sand
- Aquarium-specific gravel
- Appropriate natural rocks
- Aquarium-safe driftwood
- Aquarium-safe ceramic decorations
- Live plants
- Aquarium-safe artificial plants without sharp edges
How to Decorate a Simple Aquarium
You don't need to turn your aquarium into an underwater city. A simple setup can look beautiful while still providing fish with shelter and open swimming space.
A combination of substrate, plants, driftwood, appropriate rocks, and open swimming areas can create a natural-looking aquarium without overcrowding it.
Different fish have different priorities. Bettas benefit from plants and structures that provide resting and hiding areas. Corydoras need particular attention to the substrate, while Neon Tetras often look especially striking among plants and shaded areas.
Plants can also provide shelter for fry when keeping livebearers such as Platies and Mollies.
The Basics Every Aquarium Needs
No matter which fish you choose, the aquarium should be prepared before the fish arrive.
1. An appropriately sized aquarium
Larger aquariums generally provide more stability and give you more room to maintain suitable water conditions. A small fish does not automatically mean that a tiny container is appropriate.
2. Conditioned water
Tap water should be treated with an appropriate water conditioner to neutralize harmful substances such as chlorine and chloramine, following the product's instructions.
3. Filtration
A filter provides water movement and, most importantly, a surface where beneficial bacteria can colonize and contribute to biological filtration.
4. A completed nitrogen cycle
This is one of the most important steps for a new aquarist. Don't buy the fish on the same day you set up the aquarium.
The aquarium needs time to establish beneficial bacteria capable of processing toxic ammonia and nitrite. Water testing helps determine whether the aquarium is ready for fish.
5. Appropriate temperature
Tropical fish need a suitable and stable temperature. A simple aquarium thermometer can help monitor conditions, while a thermostatic heater may be necessary when room temperature is too low.
6. Regular maintenance
An aquarium is not something you set up once and forget. Water quality should be monitored, equipment maintained, and partial water changes performed as needed.
So, Which Fish Should You Choose?
There isn't one perfect fish for every aquarium. The better approach is to choose a species whose requirements match the aquarium you can properly maintain.
- Platy: hardy, colorful, and relatively easy to keep.
- Corydoras: active bottom-dwelling fish that need a group and suitable substrate.
- Molly: hardy and active, but best suited to harder, more alkaline water and adequate swimming space.
- Neon Tetra: small and colorful, but better suited to a mature, fully cycled aquarium and a proper school.
- Betta: a popular beginner fish when kept in a properly heated, filtered, and appropriately sized aquarium.
The key to successful fishkeeping isn't finding the fish that can tolerate the most mistakes. It's creating an environment that meets the needs of the species you choose.
You're not just bringing home a fish. You're creating a little home for it.
References
The information on fish size, water parameters, behavior, and basic care was checked against specialized aquarium and fish welfare resources:
- OATA — How to Set Up and Look After a Freshwater Tank / Aquarium
- OATA — How to Test Water Quality in Your Freshwater Tank / Aquarium
- OATA — How to Look After Platies and Swordtails
- OATA — How to Look After Guppies and Mollies
- OATA — How to Look After Siamese Fighting Fish (Bettas)
- Seriously Fish — Xiphophorus maculatus (Platy)
- Seriously Fish — Corydoras paleatus
- Seriously Fish — Poecilia sphenops (Molly)
- Seriously Fish — Paracheirodon innesi (Neon Tetra)
- Seriously Fish — Betta splendens
Care requirements can vary between individual fish, varieties, and species. Before purchasing any fish, check your local water parameters and the specific requirements of the species you plan to keep.