Following on from my list of fish suitable for beginners, here is a list of fish, all commonly available in pet shops, to avoid. Whilst most would agree with my list of best fish, this list is a little more contentious. Some of the species I’ve selected will come as a surprise and many will disagree with my choices. See what you think.
Common pleco catfish (Pterygoplichthys pardalis)
The common pleco (pronounced plecko or often just pleck) is sold in almost every shop that sells tropical fish. It is usually about 5cm long and advertised as a good algae eater. There are also “golden” varieties available. There’s no doubt this fish will eat algae and it’s also a peaceful fish in the main, keeping itself to itself and leaving even the smallest of tank mates alone.
The problem is that this fish can get big, and big fish need big tanks and have big appetites. A decent sized pleco will be over a foot (30cm) long and they don’t take that long to get this size. It requires large quantities of vegetable matter in the form of cucumber, lettuce, pellets and, sadly, aquarium plants. Of course what goes in must come out and this fish produces vast amounts of waste material which needs to be continually removed. It’s constant rooting around means aquarium decoration and equipment has to be secure and robust. In short for the typical beginner’s tank it’s a nightmare.
Main reason for inclusion in list – size. Other fish in this category include red-tailed catfish, oscar, silver shark, iridescent shark, clown loach and tinfoil barb.
Discus (Symphysodon spp.)
Known as The King of Fish, the discus is a large cichlid (pronounced SICK-lid) from the Amazon River system. It’s one of the few shoaling cichlids and in the wild is found in large groups. Discus need a large tank (six-foot is typical) and will not thrive without pristine water conditions. Many discus keepers filter their water using various high-priced pieces of equipment to remove impurities.
Feeding discus is tricky so pay special attention to diet. There are even recipes available specifically for discus. This species is prone to ill-health and some hobbyists medicate their fish regularly to eradicate worms and other parasites. There are many colour varieties available and these are not so challenging to keep as wild caught specimens.
A fish as beautiful and interesting as this is bound to attract devoted followers and there are many clubs and websites dedicated to discus and discus breeding. It’s true to say that discus-keeping is a hobby within a hobby.
Main reason for inclusion in list – difficulty. Other fish in this category include blue rams, glass catfish, hatchetfish and bumblebee gobies.
Rift lake cichlids
Dotted along the Rift Valley in East Africa are several huge lakes, each home to an astonishing variety of cichlids. The three main lakes are Victoria, Tanganyika and Malawi and each has its own distinct population of these marvellous fish. Today, scientific study of the fish here has given a fascinating insight into the power of evolution. (See The Cichlid Fishes: Nature’s Grand Experiment in Evolution by George Barlow)
The fish most often found in pet shops are from Lake Malawi and the various species are usually grouped under the name of Malawi cichlids. Beginners may be tempted to buy some of these colourful fish for their community tank but that would be a mistake for two main reasons.
- These fish have evolved a complex social structure which includes both courtship and territory displays. Consequently aggression within groups and between groups is often high. In a vast lake it’s possible to flee from an aggressive foe, no such option is available in the confines of an aquarium.
- The African lakes have a distinctive geology which means that their water has high levels of minerals and salts. The cichlids have evolved in these conditions and have bodies that can cope, most other fish do not.
It’s possible to successfully keep a mixed community of these cichlids in home aquaria but it’s best to undertake such a project only when the hobbyist has grasped the basics of fish-keeping and is not recommended for those just starting out.
Main reason for inclusion in list – aggression. Other fish in this category include oscars, jewel cichlids and bettas.
The parrot cichlid is a comical looking, colourful fish that especially appeals to young children. Unfortunately these attributes are arrived at through hybridisation and, often, artificial colouring. These fish are created by crossing two or more species of cichlid and the resulting offspring are then dyed and sold as “jellybean” cichlids. Parrot cichlids are usually infertile (as happens with most hybrids) and often have deformities such as misshapen mouths and missing fins. They are quite sizeable fish and can develop an aggressive streak. All in all they are best avoided.
Main reason for inclusion in list – hybrid. Other fish in this category include flowerhorn cichlids, many synodontis catfish and some rainbowfishes.
Okay so they’re not fish. Nevertheless many beginners make the mistake of buying aquatic frogs and adding them to their community tanks. Shops offer several different species of frogs and some, like the African clawed frog (Xenopus Laevis) can grow large. The main issue is that they don’t mix very well with most fishes. Smaller specimens can starve as they can’t compete with fast-moving fish for food and larger specimens can predate on small fishes. They are long-lived with some animals living for more than 20 years, clearly a long commitment.
It’s better to keep a separate tank for frogs and maintained according to the requirements of the species. Special food should also be given and close attention paid to water quality, a stable environment and tank furnishings.
Main reason for inclusion in list – compatibility. Others in this category include newts, crabs and terrapins.
Tiger barb (Puntius tetrazona)
A shoal of tiger barbs is a thing of beauty. Their bold black and white stripes, red nose and jaunty habit make them highly desirable. The temptation to add one or two to a community tank is very strong. It should, however be resisted. The tiger barb is so-called not only because of its stripes! To be fair, this little fish is not what you would call aggressive, in fact aquarists have coined a word to describe its habit – nippy. Tiger barbs are irresistably attracted to the fins of other fish. Especially if those fins are long and flowing and the fish slow-moving. Constant nips from tigers will quickly result in the death of the unlucky victims.
It’s often written that the secret to successfully keeping these fish with other species is to keep them in a shoal. The theory goes that any aggressive behaviour will occur within the group of barbs and not be directed at other fish in the tank. I’m skeptical of this claim though, having seen barbs continue to nip even when kept in groups of a dozen or more.
These fish do best either in a species only tank or when kept with other fast-moving, short finned robust species such as other barbs, danios and larger tetras.
Main reason for inclusion in list – nippy. Other fish in this category include serpae tetras, Buenos Aries tetras, red-tailed goodeids and many species of killifish.
Black Ghost Knifefish (Apteronotus albifrons)
The black-ghost knifefish is a fascinating fish with an unusual appearance. It is often found for sale in larger pet stores and many find homes in the community tanks of unsuspecting aquarists. The subsequent events are as predictable as they are avoidable. Each night several of the smaller fishes in the tank goes missing. The confused beginner puts it down to a mystery disease or just bad luck and buys some more. Of course the knifefish will appreciate this moonlight feast and grows rapidly. It may be quite some time before the culprit is rumbled.
Keeping a few together in a species tank is no good either. Although they may co-habit for a short while it wont be long until they become intolerant of each other and have to be split up. This fish is for the specialists only.
Main reason for inclusion in list – predatory. Other fish in this category include oscars, pike cichlids and many larger catfish.
Balloon molly (Poecilia spp.)
In recent years this new kind of fish has started to appear in the shops. Balloon mollies are distorted versions of normal fish that appear to have been squashed from nose to tail. Presumably an original, deformed, individual has been line-bred to produce the various colours that are now offered.
Interestingly, balloon varieties of other popular fish have started to appear including blue rams (Mikrogeophagus ramirezi) and even bronze corydoras (Corydoras aeneus). This suggests that the gene or genes that cause this deformity (we know it’s genetic as balloon mollies breed true) is common to all fish and fairly easy to manipulate.
Of course deformed fancy fish are nothing new and various kinds of bizarre goldfish have been available for many years. Long-finned varieties of many species are also common-place. These fish are almost always less robust than normal specimens and can be difficult if not impossible to keep and breed long-term.
Main reason for inclusion in list – deformities. Other fish in this category include fancy goldfish, balloon rams and long-finned ancistrus catfish.
Disco fish (Parambassis ranga)
It’s hard not to feel sympathy for the hard-pressed shopkeeper in these financially difficult times. Anything that helps the business stay afloat is welcomed with open arms. All the more credit then to those who’ve made the decision not to sell painted or dyed fish.
Painted glassfish, known as “disco fish”, have been around for many years. The usual species is the Indian glassfish – Parambassis ranga. The glassfish makes a good candidate for injecting with dye as it is transparent. Gaily coloured fish are attractive to small children and many end up in the tanks of inexperienced fishkeepers who are usually unaware that the colour is not natural.
Recent studies have shown that from an animal welfare perspective dyed fish have a poor time of it. The process itself is probably painful and many suffer from subsequent health problems such as cysts. It’s also reported that the colour fades in those specimens which do live for a reasonable time.
All fishkeepers are encouraged to avoid buying these fish and to actively encourage those shops who have signed the pledge against dyed fish.
Main reason for inclusion in list – artificial colouring. Other fish in this category include Jellybean cichlids and blueberry tetras.
Guppy (Poecilia reticulata)
The guppy has been a staple of the aquarium trade for decades and many a long and rewarding hobby has been launched by the purchase of a fancy male guppy. So why are they on this list then?
The problem with modern guppies is that they are often prone to ill-health. The hardy guppy of yesteryear has been replaced by a fragile creature that is liable to drop dead as soon as it sees your tank. And it’s not just guppies either. Other livebearers such as mollies and platies seem to be plagued by skin diseases and can often be seen gathered at the top of a dealer’s tank shimmying away with their fins clamped.
The reasons for this are not altogether clear. It may be due to excessive line breeding or over use of medications by commercial breeders, or perhaps a combination of both.
Occasionally wild guppies are available and these are usually very hardy. It’s also worth joining your local fish club who will be able to put you in touch with a breeder who will undoubtedly have healthy stock.
Another problem with guppies is that if you do get healthy specimens they will set about doing what guppies do best – breed. And boy can they breed. Their nickname of “million fish” is no exaggeration. A female can drop fry every 3 weeks or so and they themselves can produce fry within 3 months. The hapless guppy keeper can soon find themselves overwhelmed with guppies. Most shops will only take nicely coloured adult fish and even then for only a few pence. The vast shoals of mutts usually produced will present a real problem.
Guppies can make a fascinating and rewarding breeding project and many hobbyists keep nothing else. There are however better fish with which to begin your fish-keeping adventure.
Main reason for inclusion in list – health problems. Other fish in this category include neon tetras and dwarf gouramis.