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Specialty Species Can Cause Special Problems


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A surprising one at the top of the list is the common goldfish! Initiates in the tropical fish field are usually not aware that goldfish like chewing on fresh natural plants and that they need quite a lot of oxygenation (water surface movement and good filtration). Goldfish are also susceptible to ich and lice, and easily pass these on to other tank inhabitants. This does not imply that you need to cease and desist from buying goldfish. Just remain aware that they certainly can be put in a community tank, but that their natural habits might preclude you from putting in plants, or you may have to ensure that your plant growth exceeds the goldfishs' appetites!


Another beautiful but large fish that the hobbyist should be very careful about before buying is the Arowana, or Osteoglossidae family. This very large specimen might be sold in aquarium shops as a small juvenile, perhaps no larger than 4-6". The unaware buyer might assume that this fish will grow a bit, but may not understand that it will grow a lot, up to four feet in length! When it begins reaching over a foot, it will also (even before this, actually) begin to jump upwards and out of the tank if you don't have it covered very well (screen across the entire top). If you are using a glass cover, an Arowana that is over a foot or two long can break the glass cover. This species also requires fresh food (live, normally) consisting of later very large goldfish. Some of us are a little squeamish in this regard (me) and won't want to feed little unsuspecting live fish to this carnivore. He can and will sometimes take dead fish, but it.s the live kind that he prefers.

Water conditions are tropical, from 75-low 80s, and slightly acidic (pH of 6 or 6.5). Soft water recommended. A close relative is the Asian Arowana, Scleropages Formosus, a slightly smaller version of this species and one that takes somewhat warmer water readily (up to 85F). This does not mean that it should be kept with discus! Remember the Arowana is a predator. Water quality for all Arowana should be high, and filtered in the best of traditions.

Clown Knifefish

The clown knifefish (Notopterus Chitala) grows up to 40 inches, and is thus a candidate for caution. This fish is possibly even more viscous in its fresh-mean eating habits, and will feed on plants and fish. Since it is an aggressive, and belligerent fish, it is recommended that the clown knifefish be maintained in a separate tank apart from other fish. An interesting note on the predatory nature of the clown knifefish is that it will prey at night, darting in on other fish species who might be trying to take a good sleep from a hard day's work! Again, filtration is important to this fish. Actually, this last piece of advice applies to almost any fish species.

Alligator Gar

Those who don't know the Alligator Gar (Lepisosteus Tristoechus, will be surprised to find that this fish, also a predator (a lurking one at that), grows to almost 120 inches (6 feet). It will accept water temperatures ranging from the mid-60s up to 80F, and a neutral pH is fine.

Electric Eel

The more esoteric fishkeeper might be tempted to purchase an Electrophorus Electricus, or Electric Eel. This carnivorous fish can deliver a horse-paralyzing bolt of electricity, so handling the fish and keeping it in any tank is a question of personal health. Growing up to some 7 feet, this eel can be tamed and taught to eat from your hand, but anyone venturing this far might also own a Mastiff. Why own a fish like this?


The family Mormyridae is another fish that should be kept with caution. Also an electrical field generating fish, this will grow to much smaller dimensions than the fish cited above, only to some 6-18 inches, depending on the species kept. They are also difficult to keep, despite their apparent attractiveness. Peter's long-nosed elephant fish is perhaps the most well-known Mormyridae. Preferring brackish water with a pH ranging from 6-8 (again, depending on the species), this fish is carnivorous and very little information is known regarding its breeding habits.


Prior to the end of this article, I'll name off some other fish species that you will want to ring an alarm bell in your mind if you every run across them, or if someone wants to sell you one or give you one. Some of the alarm might be from the possibility that they are omnivorous or carnivorous, or that they just grow to too large a size to keep at home without tremendous cost implications. Are you willing to part with your PC to keep your aquarium?

The tank busters, or fish that are too large, are in one category, and perhaps the second and third categories might be being carnivorous and sensitive to water conditions. These three factors (size, whether they eat other fish or not, and what kind of water conditions they require) should always be in the front of your mind when looking at a new fish. Finally, on to some of the species that you may wish to steer clear of, or at least educate and prepare yourself well in advance. Roloff's Kribensis: omnivorous. Redheaded cichlid: omnivorous. River barb: 20 inches and omnivorous. The Siamese Tiger (Datnoides Microlepis), which can grow up to slightly under a foot and a half and which will chase and swallow anything it can swallow!

As you can see, there are vast numbers of species that should not be purchased by the casual fishkeeper. The responsibility for ensuring that the right fish reaches the right fishkeeper is a joint one. First, with the retailer who should never sell anyone a fish he or she can't properly take care of. Second, with the fishkeeper who must educate himself/herself constantly to be able to walk into a retailer somewhat informed and thus able to make a responsible and humane decision.

More in August.


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