5 Popular Freshwater Fish to Avoid as a Beginner

Starting a freshwater aquarium is an exciting venture, but choosing the right fish is crucial to the longterm enjoyment of your tank, especially if you’re a beginner. I remember the first time I walked into a fish store, ready to get my first fish. The seemingly endless options of colorful, unique, and fascinating fish were overwhelming. I wanted to take them all home! But I soon learned that some fish, although popular, can present significant challenges for the new aquarist. Here’s my take on the top five worst beginner freshwater aquarium fish that are extremely common, and some better alternatives to consider.

1. Common Plecostomus (Hypostomus plecostomus)

Why They’re Popular: Commonly known as “plecos,” these algae-eating fish are often recommended by your local LFS or pet store to unsuspecting buyers for their ability to keep tanks “clean”. Another thing to be aware of is many plecos are misidentified at the fish store, meaning you need to really know the physical traits of the species you want, or you may end up with the wrong specimen!

Challenges:

• Size: Common plecos have the ability to grow up to 18 inches, which requires a much larger tank than most beginners tend to have. In order to thrive at full size, they require at least a 200-gallon tank in the 6-foot-long dimension range. Ideally, a small pond or pool is the best habitat for these large armored catfish once fully grown.
• Diet: Needing more than just algae to thrive, this particular species, Hypostomus plecostomus, is omnivorous, requiring a varied diet including vegetables and specialized pellets.
• Tank Conditions: They produce a significant amount of waste, necessitating robust filtration and regular water changes.
• Algae Control: Here is the main caveat, it is not even guaranteed that your plecos will eat the tank’s algae and keep your aquarium clean. Even if they do eat your algae, their high waste production can lead to elevated nitrate levels, and more nitrates can equal more algae. This means you’ll likely end up facing the same algae issue you were trying to solve in the first place.
• Growth Rate: The only saving grace of the common pleco is its somewhat slower growth rate compared to other large-sized fish. Even then, you still end up with a monster-sized fish in a matter of a few years.

Alternative: Consider smaller algae-eaters like Otocinclus or Amano shrimp, which are easier to manage in smaller tanks. There are also quite a few species of pleco that are smaller and better suited for home aquaria, such as the Bristlenose Pleco or Clown Pleco.

2. Angelfish (Pterophyllum scalare)

Why They’re Popular: Angelfish are admired for their graceful appearance and unique shape, making them a visually appealing choice.

A Juvenile Altum Angelfish

Challenges:

• Unpredictable Behavior: Contrary to their seemingly docile looks, angelfish can be very unpredictable in their behavior, often becoming aggressive and territorial with different fish, meaning that tankmates have to be carefully thought out.
• Fin Nipping: Due to their size and elongated fins, they can be prone to fin nipping. This means quick and feisty or territorial fish should be avoided.
• Small Fish: Very small fish are not a good idea as they can be eaten when angelfish reach their maximum size of around 5 to 6 inches in height.
• Water Quality: Although they are hardier now as generations have been bred to live in home aquaria, they still need very good water parameters to grow and reach their full potential without stunting.
• Tank Size: The smallest tank size an angelfish should be in is 29 gallons for 1 fully grown adult. If you want a decent amount of tankmates or other angels, a 55 or 75-gallon tank is recommended.

Alternative: Consider Pearl Gouramis or Rainbowfish, which offer beautiful colors and more predictable behavior, making them suitable for community tanks.

3. Oscar Fish (Astronotus ocellatus)

Why They’re Popular: Oscars are known for their intelligence, intricate patterns, and interactive behavior, often known as the water dogs of the fish world., they They are also popular due to the various new morphs available in the hobby, such as the Bumblebee Oscar and the Long Fin variant.

Challenges:

• Size and Growth Rate: Oscars grow rapidly, reaching up to 12-14 inches, and need a minimum 75-gallon tank. In order to add any fish or a second Oscar, you will need at least 125 gallons.
• Aggression and Territoriality: Although Oscars are not as aggressive as one might think, they can still become territorial as they age and will prey on tank mates small enough to fit in their mouths. The main challenge is keeping an Oscar in a community tank. Smaller fish can be eaten, and while larger fish might be suitable, you’ll need a larger tank, often in the 150-plus gallon range. The most ideal yet often underutilized option is to keep an Oscar by itself in a 75-gallon tank.
• Messy Eaters: Oscars are messy eaters, which adds to filtration challenges. If filtration is not sufficient, Oscars can be prone to Hole in the Head disease.
• Diet: They have a voracious appetite and require a varied diet, leading to increased waste and higher maintenance. Experienced keepers usually have to manage how often they feed them as overfeeding is easily accomplished with these fish.

Alternative: Consider the Chocolate Cichlid, which is less temperamental and slightly smaller. Other smaller cichlids like Keyhole Cichlids or the Blue Acara are also great alternatives for community tanks.

4. Bala Shark (Balantiocheilos melanopterus)

Why They’re Popular: Bala sharks are striking with their sleek, shiny bodies and active swimming behavior, making them a captivating addition to any tank.

Challenges:

• Size: Bala sharks can grow up to 14 inches! Although the more common size in home aquaria is around 8-10 inches. The main issue here for novice aquarists is that Bala sharks thrive in groups, and when you couple this with their active behavior and large size, you are looking at providing them with tanks of 200 plus gallons and on to fully satisfy their needs. Most people just simply do not have the space to keep them!
• Schooling Fish: They thrive in groups, so a beginner would need to keep multiple Bala sharks, further increasing the required tank size. At least 3 would be the minimum and 6 plus would be the ideal!

• Jumpers: Known for jumping out of tanks, they require secure lids to prevent escapes. Regular glass tops will not work unless fastened as these fish can generate a decent amount of power and air time when spooked.

Alternative: Try Denison Barbs, another type of cyprinid as well and add a pop of color. They are more suitable for standard beginner tanks.

5. Comet Goldfish (Carassius auratus)

Why They’re Popular: Often seen as the quintessential beginner fish, comets are as hardy as they come and have a long lifespan.

Challenges:

• Size and Space: Comet goldfish can grow up to 12 inches and produce a lot of waste, needing large tanks (at least 55 gallons) or outdoor ponds. A good rule of thumb is about 50 gallons of water per comet goldfish.
• Temperature Requirements: They prefer cooler water, making it challenging to keep them with other common tropical fish. These fish are best suited for tanks or habitats dedicated to cold water species, typically alongside other goldfish.
• Waste Production: Goldfish produce copious amounts of waste compared to other fish their size, meaning heavy filtration is a must.
• Longevity: With proper care, they can on average live for over a decade, which may be a longer commitment than some beginners are prepared for. The oldest known goldfish, named Tish, lived to be a whopping 43 years old!

Alternative: Fancy goldfish varieties like Red Ryukins are more manageable in size and have similar care requirements. Comet goldfish, unlike their fancy counterparts, thrive better in outdoor ponds or large stock tanks due to their larger size and cooler water needs.

Recap

Starting a freshwater aquarium is a rewarding hobby, but it’s essential to choose the right fish, especially as a beginner. Here’s a quick analysis of the challenges each of these popular fish present:

• Common Plecostomus: While they can help with algae control, their large size and waste production make them impractical for most home aquariums. Consider smaller pleco species or alternative algae-eaters.
• Angelfish: Their beauty is offset by their unpredictable behavior, aggression, and need for specific tank conditions. They can also prey on smaller fish and can fight amongst each other. Opt for more peaceful community fish like Pearl Gouramis or Rainbowfish.
• Oscar Fish: Their intelligence and personality are appealing, but their size and territorial nature require more experienced care. Adding other fish or a second Oscar necessitates a tank of at least 125 gallons, and community tanks require 200-plus gallon setups. Smaller, less aggressive cichlids like the Chocolate Cichlid, Keyhole Cichlid, or Blue Acara are better choices if looking for something similar.
• Bala Shark: Impressive swimmers, but their size and need for large groups and tanks make them unsuitable for beginners. Smaller schooling fish like Denison Barbs are a more manageable option.
• Comet Goldfish: Hardy and long-lived, but their size, cooler water requirements, and waste production pose challenges. Fancy goldfish varieties like the fancy goldfish are a more practical alternative for new aquarists.

Conclusion

By choosing more suitable alternatives, new aquarists can enjoy a more successful and rewarding aquarium experience. Remember, research and planning are key to a thriving aquarium, so always consider the specific needs of any fish before bringing them home. Happy fishkeeping!

It’s important to note that while this read is filled with as much factual information possible, the fish chosen are based on personal experience and opinion, which can differ for everyone. Just because a fish is listed here doesn’t mean you cannot keep it. This post is simply to warn the unsuspecting novice of the considerations and challenges these fish may present, while also highlighting easier options to start with. At the end of the day, as long as you can satisfy the requirements almost any fish can be a great first fish.

What other common fish do you think are challenging for beginners?

Happy Fishkeeping!