Top 7 WORST Beginner Fish! (BEWARE)

Starting a new aquarium is an exciting adventure, but it’s essential to choose the right fish, especially when you’re new to the hobby.

Some species require more experience or specific care to thrive, and selecting them can lead to frustration or even failure.

To help you build a successful aquarium, we’ve compiled a list of seven fish you should avoid as a beginner.

We'll explain why they can be tricky to care for, what their specific needs are, and suggest some alternative species that are better suited for newcomers.

1. Moorish Idol (Zanclus cornutus)

The Moorish Idol is often featured in popular aquarium setups, but it’s one of the most challenging fish for beginners.

This species is notorious for its sensitivity and high maintenance, making it unsuitable for less experienced hobbyists.

Why You Should Avoid It

Moorish Idols require perfect water conditions and can easily succumb to diseases if there are fluctuations in water parameters. They are highly susceptible to stress and require a mature aquarium with stable conditions.

Additionally, they are reef fish, meaning they need live rock and a well-established system to thrive.

Requirements

• Large aquarium (at least 100 gallons)

• Stable water quality with minimal fluctuations

• Live rock for grazing

• Experienced aquarist knowledge

Recommended Alternative

For beginners, consider the clownfish or goby fish. These species are more adaptable, requiring less maintenance and performing well in a variety of tank setups.

2. Angelfish (Pterophyllum scalare)

Angelfish are beautiful, majestic fish, but they are not the easiest species for novice aquarists. While they can thrive in the right conditions, they can be aggressive and often do not do well in community tanks with smaller or more docile fish.

Why You Should Avoid It

Angelfish can be territorial, especially during breeding. They also require specific water conditions and a larger tank to swim comfortably. If kept in a smaller tank, they may become stressed, affecting their health.

Requirements

• Large tank (at least 55 gallons)

• Stable water conditions

• Plenty of hiding places for less aggressive tankmates

Recommended Alternative

The neon tetra or guppy is a great option for beginners. These fish are colorful, peaceful, and easy to care for, making them perfect for community tanks.

3. Red Tail Shark (Epalzeorhynchos frenatum)

The Red Tail Shark, also known as the Rainbow Shark, is known for its aggressive behavior and its territorial nature, especially when it feels threatened.

It may not be the best choice for beginners, as its aggressive tendencies can disrupt a peaceful aquarium.

Why You Should Avoid It

Red Tail Sharks are territorial and will chase other fish, particularly if they feel their space is being invaded.

They also require a large tank and prefer hiding spots. When stressed, they can develop health issues, making them a challenging species to care for.

Requirements

• Large tank (at least 75 gallons)

• Plenty of hiding spots to reduce aggression

• Single-species tank or with other similarly sized, non-aggressive fish

Recommended Alternative

Consider the harlequin rasbora or the platies, which are peaceful and adapt well to smaller tanks.

4. Discus (Symphysodon spp.)

Discus fish are incredibly striking and beautiful, but they are high-maintenance and require very specific water conditions that are difficult for beginners to replicate.

They are also sensitive to changes in water quality, temperature, and diet.

Why You Should Avoid It

Discus need soft, acidic water and higher temperatures, along with a very stable environment. They are sensitive to diseases and can easily succumb to stress.

For beginners, maintaining such delicate conditions can be overwhelming and lead to problems down the road.

Requirements

• Large tank (at least 75 gallons)

• Soft, acidic water

• High temperature between 82°F and 88°F (27°C–31°C)

• Experienced care and frequent water changes

Recommended Alternative

Instead of discus, consider the betta fish or cichlids, which are easier to care for and require less specialized care.

5. Piranha (Pygocentrus nattereri)

Piranhas are widely known for their sharp teeth and aggressive nature. While they can be an intriguing choice for an aquarium, they are not suitable for beginner fishkeepers.

Why You Should Avoid It

Piranhas require very specific care, especially regarding their diet, water quality, and tank size. They also need to be kept in groups for social stability, which can create more challenges for beginners.

Additionally, their aggressive nature can make them difficult to house with other fish.

Requirements

• Large tank (at least 100 gallons)

• Specialized diet (live or frozen foods)

• Proper filtration to maintain clean water

• Social environment with a group of Piranhas

Recommended Alternative

A better option is the tetras or barbs, which offer a wide variety of colors and patterns without the aggressive behavior associated with piranhas.

6. Emperor Angelfish (Pomacanthus imperator)

Another beautiful, yet challenging, species is the Emperor Angelfish. While it is a popular choice in marine tanks, it requires a high level of care, particularly in terms of water conditions and space.

Why You Should Avoid It

Emperor Angelfish are sensitive to water quality and need a very large tank.

Additionally, they may require a very specific diet and must be kept with larger, more robust fish, as they can become territorial. This species also tends to be quite sensitive to stress.

Requirements

• Large tank (at least 150 gallons)

• Stable water conditions

• Varied diet, including algae and meaty foods

• Experienced care and knowledge of marine setups

Recommended Alternative

Instead of the Emperor Angelfish, consider the clownfish or the blennies, which are more adaptable and easier to care for in a marine setup.

7. Butterfly Fish (Chaetodon spp.)

Butterfly fish are another species commonly found in reef tanks, but they are often too delicate and specific in their needs for beginner aquarists.

Why You Should Avoid It

Butterfly fish need stable, pristine water conditions and a well-established reef tank. They are often difficult to acclimate to a new tank and can be vulnerable to disease if not kept in the right environment.

Additionally, they are often more sensitive to tankmates and may become stressed easily.

Requirements

• Large, well-established reef tank (at least 100 gallons)

• Stable water parameters (temperature, salinity, pH)

• Appropriate tankmates that are not overly aggressive

Recommended Alternative

Instead of the Butterfly Fish, the cardinalfish or damselfish are both great options for beginner reef aquariums.

General Tips for Beginner Fishkeepers

Starting an aquarium is about more than just picking the right fish. Here are some essential tips to help you succeed as a beginner:

• Research is key: Always research the species you plan to keep. Each fish has its own set of care requirements, and being well-informed will help you avoid costly mistakes.

• Water quality is critical: Regular water changes and maintaining stable water parameters are essential for the health of your fish.

• Start small: Begin with a smaller, manageable tank and gradually add fish as you gain experience. This will help you avoid the temptation of overcrowding, which can lead to stress and health problems for your fish.

• Choose hardy species: Opt for fish that are well-known for their ability to adapt to a variety of water conditions. These species are often more forgiving and easier to care for.

• Be patient: Starting an aquarium requires time and patience. Don’t rush to add fish, and allow your tank to stabilize before adding new inhabitants.

Conclusion: Build Your Aquarium with Care

Choosing the right fish is one of the most important steps in creating a successful aquarium.

While the species we’ve discussed here may look appealing, they are best left to more experienced aquarists who can meet their specific care requirements.

As a beginner, it’s essential to choose fish that are hardy, easy to care for, and can thrive in your tank’s environment.

By doing thorough research, maintaining proper water quality, and being patient, you can create a thriving aquarium that brings beauty and joy to your home.

Source: KeepingFishSimple

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