If you’re a beginner hobbyist, you may feel that you have a lot of choices when deciding which fish to keep in your first aquarium. There are freshwater fish available in a wide variety of colors and shapes and so many of them are exquisite. But before you make your decision based on looks alone, it’s important to understand that different types of fish need different levels of care. We’ve already featured a few types here that are ideal for beginners to keep. Let’s take a look now at saltwater fish that are more challenging to keep in a home aquarium and why these fish should only be kept by experienced hobbyists.
1. Red-Tailed Shark
This type of fish is popular and for good reason. It has striking colors, and it’s shaped like a shark, even though it’s a lot smaller. The red-tailed shark is not particularly difficult to take care of, but it is extremely territorial. This means that it is not possible to keep other red-tailed sharks or even similar species together at all. You’d also not be able to populate your tank with more timid fish because the red-tailed shark is likely to pick on them. 2. Pacu
Some hobbyists know this fish as the piranha’s vegetarian cousin. In reality, Pacus are omnivores and need a varied diet that includes fresh vegetables. And that’s not the only thing that makes it challenging to keep them. These fish grow to quite a large size. Most of them are sold when they’re around five centimetres to eight centimetres long. But don’t be fooled—over the years, these fish could outgrow a home aquarium and will probably need an outdoor pond. Pacus often grow up to over 4.5 kilograms in weight. 3. Oscar
Oscars are widely available in juvenile sizes and highly popular. They are also capable of growing to a large size and will eat just about any other fish that can fit into their mouths. Some of the experienced hobbyists who enjoy keeping Oscars use goldfish and other small fish to provide for their diet. While that may not be necessary, a large tank is and that is why this type of fish is not typically recommended for a beginner. 4. Plecostomus
Many people use these fish to sort out their algae problems. However, the Plecostomus is yet another fish that gets really big, even bigger than the Pacu and the Oscar. They are usually sold when they’re around 7.5 centimetres to 10 centimetres long. Before you know it, though, they can grow to be over 30 centimetres long. Besides the size issues, these fish also have a tendency to do quite a number on your tank, so aquarium maintenance could be a bit more time-consuming, especially as they get bigger. 5. Silver Arowana
Sensitive, temperamental, and yet another fish that grows very large in size, the Silver Arowana needs an aquarium that is at least three times its length. Considering they can grow up to over 90 centimetres, you’ll need a rather large tank to keep adult Silver Arowanas. 6. Discus
Some of the most beautiful fish you can find, discus are also calm and peaceful. Unfortunately, they are also highly sensitive to water parameters and need a large, tall aquarium with a lot of rooted and floating plants. The high level of care required makes the discus only suitable to more experienced hobbyists. 7. Glass Catfish
Glass Catfish are super interesting. Because of their transparent bodies, they are fascinating to watch. However, these fish are susceptible to bacterial infections. They are also shoaling fish so they should be kept with a minimum of six of their own kind to keep them company. Without these conditions, they are likely to perish in a community aquarium.
8. Bala shark
Another fish with a shark-like shape is the Bala Shark, which can grow to over 30 centimetres, making a small or medium-sized tank unsuitable for long. The Bala Shark is a relatively peaceful and friendly fish and thrives in groups of at least six fish. You’ll need a really large tank to accommodate them and all their friends. 9. Octocinclus
This sucker-mouth catfish is delicate and needs to be in a meticulously maintained environment, or else it simply won’t survive. The water in the tank must be pristine and have good flow over a fine substrate and a lot of live plants and rocks. It is also challenging to maintain the Octocinclus diet as they are herbivores and need algae tablets as well as vegetables like zucchini, peas, and lettuce. 10. African Cichlid
Probably one of the most beautiful fish available, the colorful African Cichlid will be a tempting choice for beginners. Caring for them is tricky because they need weekly water changes and pristine water. Another problem is their aggression. These beautiful fish are highly territorial and will almost certainly attack and kill other fish in the tank. They are also prone to fighting with each other, especially when water conditions are not perfect.