Saltwater Species That Should Not be Kept by Beginners (and Sometimes not Even by the Experienced)

It is all too common to hear that a beginner has run into severe problems due to improper research. Often they see a “really cool” fish at the store and just have to have it or they get infatuated with the idea of keeping something like a shark. People warn them about these species, but it doesn’t matter in many cases. This article is meant to bring to light some species that should never be kept except by experience aquarists with appropriate setups (and in some cases not even by experience hobbyists).

This article is not meant to be condescending, but sometimes species are simply not appropriate for a beginner tank.

Sharks

Many people love the idea of having a mean looking shark in their aquarium. They will often enter a store and see a juvenile shark that doesn’t look too big. What they fail to realize is that most sharks will soon outgrow their tank (I’ve even heard of people buying juvenile Nurse Sharks that will end up reaching lengths of 14 feet!). For this reason, sharks should be avoided at all cost (by both beginning and experienced fish keepers) except if you are willing to house them in a huge tank with a huge filtration system. When I say huge, I do not mean a 150 gallon tank. I mean a HUGE tank. Sharks need a ton of space to swim and they produce a massive bio-load on your tank. Leave sharks in the ocean where they belong.

If you really cannot escape the idea of getting a shark then stick to the sharks that stay small and do not move as much. Examples include certain Bamboo sharks and the Coral Catshark. Even with these, you are looking at adult lengths of 2.5-3 feet so a minimum tank of 180 gallons should be used.

Rays

Again most rays simply get too big for the normal aquarium. They require a huge surface area and a very specific setup to keep alive. You need to be very exact in your selection of other inhabitants and setup the aquarium so the ray does not get damaged. Rays can also injure the aquarists if he/she is not careful. As with sharks, it is generally a good idea to leave rays alone unless you are willing to invest in setting up a massive aquarium with the proper environment.

Mandarin Dragonets

These are sometimes called Mandarin Gobies even though they are not gobies. They require large pod colonies in established tanks to survive and will generally not learn to eat prepared foods (although certain individuals can and you should ask your fish store before buying if you decide to purchase one). If they are kept in a small tank or a tank that is not established, they will slowly starve to death. This is not to say you can never keep this species as many people do, but they are best left alone until you acquire some experience.

Moorish Idol

Again, it is possible to keep these fish, but for every one that survives in captivity, hundreds die. They are highly susceptible to shipping disease and stress and require tanks of 200 gallons or more. Most die within a year and very few live greatly beyond this. Even experienced aquarists should shy away from this in order to curb the terrible practice of capturing and importing them when they have such a high mortality rate.

Octopus

These are highly intelligent, aggressive, delicate, and usually need to be kept in a tank with a single species and nothing else. They do not live very long and are excellent escape artists requiring a sealed lid (there are even stories of them escaping from lids being held down by bricks). Do not ever keep an octopus in your aquarium no matter what your experience level.

Morey Eels

There are some eels that can be kept in aquariums, but it can sometimes be hard to decipher which ones are the species that stay small and which ones will soon reach two feet when you’re staring at a tank in your fish store. Large eels grow very fast and will eat even large fish in your tank. Even the commonly sold Snowflake eel can eat larger fish species. They will also place a huge bio-load on your tank. If you decide to get an eel, make sure you do your research and are absolutely sure what kind you are getting. That 6” really cool looking thing could soon turn into a two foot monster, eating anything you bought to put in your tank.

Butterflyfishes

These are best left to experienced aquarists (and even then, only a few species are hardy enough to survive in captivity) due to their general dislike of prepared foods and susceptibility to disease. They also will eat polyps and anemones making them non-reef safe. Their specialized diet makes them only suitable to a select few individuals willing to provide it.

Angelfish and Tangs

As a general rule, these fish should only be placed in aquariums that have been established for 9-12 months and where they have plenty of micro algae to graze on. Most species also attain large adult sizes and require large tanks. They are also susceptible to a number of diseases and are best left alone until you gain some experience.

Seahorses

These can be kept in an aquarium if you provide the appropriate environment. However, you must do a ton of research and really understand their needs before buying one. If you think you can just put one in your saltwater tank and watch it because it looks neat, you are sadly mistaken.

Anemones

Anemones require strong lighting and excellent water conditions. Even many experienced hobbyists are shying away from them due to our increased knowledge of the symbiotic relationship they share with fish in the ocean.

Conclusion

It can be hard to ignore those beautiful specimens you see in the fish store, but it is important to do so for several reasons. For one, the specimen will more than likely die in your setup and you will be left frustrated. Secondly, if you continue to buy these species, they will continue to be imported. As long as the demand is there, people will sell these inappropriate species.