There is, of course, no such thing as the perfect fish. Every fish has its Achilles' heel (or should that be Achilles' fin?), but these fish are very close to being perfect. The species listed here are invariably well mannered in the aquarium, attractive to look at, and not difficult to find at your local tropical fish store. They really are fish that you can run out right now and buy, knowing that they will work well in your community tank. Probably. Well, that's the point of this article. Even almost perfect fish have their needs, and these fish have been chosen to illustrate this point. While on the scale of things these are 'easy' fish compared with stuff like mbu puffers and red-tailed catfish, that's no reason to treat them badly. 

The species discussed below all have their own quite specific needs, in each case contrasting with the other fish on the list. I hope that by the end of this article you'll have some idea of the range of things to consider before buying your fish, even ones marketed as reliable, all-rounder community fish. This list also happens to include some of my very favourite fish, which just goes to show that even 'common' fish can be interesting and entertaining. If anything, the hallmark of a serious fishkeeper is that they take as good care of a bunch of guppies or goldfish as they would some rare and exotic cichlid. So, without further ado, as they say at the Oscars, let's have a look at the nominations for the role of almost perfect fish!  

5                     Bumblebee gobies, Brachygobius spp. 

The good:            A colourful character that does great in hard, alkaline water

The bad:              Live or frozen foods -- it won't eat flake! 

These delightful little gobies are among the nicest fish in the hobby. Good specimens have bright yellow bands set against a black background, and really grab your attention despite their size. They aren't all that active, but they are territorial, so while they don't need a huge amount of space you do need to make sure each fish has its own territory. The easiest way to do this is make sure there are plenty of shells or caves in the tank, and the gobies will do the rest. It's quite good fun to watch these fish go about their business: they might seem a bit sleepy, but they defend their homes with remarkable courage! They tend to ignore other fish, and for the most part other fish ignore them; some people have even suggested that their black-and-yellow colours are a warning that they taste bad or are poisonous. Even so, it wouldn't be wise to rely on this to keep them safe from substantially larger predatory fish. 

Anyway, with bumblebee gobies what you get is a peaceful, strikingly coloured little fish that will work nicely in any aquarium with hard water (and preferably a bit of salt added). Whether or not they are strictly speaking brackish water fish is a debatable point. All three of the species commonly sold in tropical fish stores are know to live and breed in completely fresh water, and there is variation within each species, with populations found in estuaries needing salt and the ones found further upstream doing fine in fresh water. Some populations inhabit soft, acidic waters like those favoured by many other Asian freshwater fish, while others can be adapted to live and breed in full-strength seawater! However, most of the bumblebee gobies traded commercially seem to do best in hard, alkaline water with a little salt added. 

Incidentally, the species sold are Brachygobius doriae, Brachygobius nunus, and Brachygobius sabanus. They are collected indiscriminately, so there's no reason to assume a single batch of fish contains just one species. Identifying the gobies you have to species level is extremely difficult; and for the aquarist it is probably pointless since all three require the same water conditions. Goby experts consider the only sure-fire way to name a bumblebee goby is to examine a dead specimen under a microscope -- something few aquarists are going to want to do. Moreover, almost all photographs published in books and on web sites are incorrectly named, so they aren't much help either. About the only certainty is that one species you won't have is Brachygobius xanthozona -- although the name is widely used in the hobby, this goby is so rare that most museums don't even have specimens of it, let alone tropical fish stores! 

Not that what your bumblebee gobies are actually called matters all that much, as the they all have much the same requirements as far as water conditions and feeding go. Which brings us to the prime flaw of these fine little fishes: they won't eat flake. Aquarists like their fish to eat flake and pellet food; for one thing it's inexpensive and convenient, but more importantly in the long run, good quality flake food is carefully prepared to ensure your fish get all the nutrition they need. However, bumblebee gobies just won't eat flake. They might have a bite, but they'll spit it out, and you'll definitely need to make other plans as far as feeding goes. Frozen foods such as bloodworms, lobster eggs, and mosquito larvae are probably the easiest option to take, though live foods are perhaps best. Even assuming your gobies will eat what you're offering, you need to make sure they get a chance to feed. In many community tanks the other fish will eat up all the food before the gobies get a mouthful, so if you want to mix bumblebees with other kinds of fish, choose fish that eat more slowly or ones that don't take food from the substrate (like halfbeaks).

4                     Royal Plec, Panaque nigrolineatus 

The good:            Classy algae eater that's adaptable and hardy

The bad:              Delicate at first, so needs some TLC to begin with 

Almost everyone with a community tank keeps a Plec of some kind, whether its one of the dwarf Ancistrus or one of the giants, these fish have firmly rooted themselves in the hobby as first-rate scavengers and algae eaters. Nevertheless, many are rather drab, particularly the less expensive but rather hardy species that people setting up their first community tank often end up purchasing. There are of course many very handsome Plecs, but they're often expensive and difficult to find. Falling between these two extremes is the royal Plec, a medium sized Plec that is a bit more expensive than the average catfish but widely sold and easy to find. It is a very good-looking fish, with a body covered in light and dark grey stripes and bright red eyes. A variety of regional varieties and subspecies are sold under the royal Plec moniker, often referred to by catalogue numbers known as 'L-numbers', for example a royal Plec with a greenish hue is known as the olive royal Plec, L027b. 

Regardless of the actual name or number of the fish you have, all royal Plecs can be kept be in the same basic way. Like other Plecs, they are primarily nocturnal herbivores and particularly relish green algae and its substitutes (such as algae wafers, blanched lettuce, and strips of courgette). One peculiar dietary requirement is wood: they do appear to eat this stuff and fare badly without it, so some bogwood should always be placed in a tank containing royal Plecs. They are retiring animals and do best if given a cave or hiding place of some sort, and can be territorial if forced to compete for space with other catfish; but they are otherwise very peaceful and will not harm other any other fish, even very small ones like livebearer fry. As far as water conditions go, they are relatively tolerant of pH and hardness (my specimen is over ten years old and has always been kept in the hard, alkaline water typical of South East England). What royal Plecs do need is a decent current and plenty of oxygen as these are fish of fast flowing streams rather than swamps or ditches. In this regard they are much less adaptable than, say, common Plecs such as Hypostomus punctatus that are able to breathe air if they need to. 

Although a big if slow growing fish -- typically reaching 15 to 20 cm in home aquaria -- this isn't the main problem with the royal Plec. In fact, this moderate size makes them good companions for medium to large fish such as gouramis, climbing perch, angelfish, and spiny eels. No, the thing that prospective owners need to brace themselves for is the rather tricky phase immediately after buying the fish and bringing it home. Like a lot of the wild-caught Plecs, these fish don't travel well, and by the time they arrive in your local tropical fish store will likely be half-starved and severely stressed. Many specimens fail to survive because their owners do not give them optimal water conditions and all the food they need to put some weight back on. There is in fact a very good argument for placing these fish into a quarantine tank for the first few weeks so that the aquarist can watch the fish carefully and make sure that it is eating well. Obviously slicing up some vegetables is much less taxing that trying to wean a predatory fish onto dead food, but still, this is something that the aquarist needs to tackle diligently if his new fish is going to do well. 

It is just as important to make sure that you buy a fish that isn't so thin that it isn't going to make it whatever you do: avoid specimens with sunken eyes and hollow bellies. The best retailers make sure their fish are feeding well before they sell them, and given that these fish are pricey to begin with, it's well worth your while tracking down a retailer with a good reputation for handling South American catfish generally.

3                     West African Butterflyfish, Pantodon buchholzi 

The good:            Unique fish with lots of character

The bad:              Predatory 

Many aquarists like to keep oddballs of one kind or another. Most are large, difficult to keep, or expensive; freshwater stingrays are classic examples of this. But are there oddballs for the community tank? One that springs to mind is the Butterflyfish, a close relative of the Arowanas of South America, and if you look at its head with its upturned mouth you can certainly see the family resemblance. The Butterflyfish is a strange-looking beast, with pelvic fins that look like feelers and pectoral fins that look like wings. 

Butterflyfish do best in tanks with soft, acidic water filtered through peat, and they love planted tanks. They normally stay close to the surface and like to hide beneath floating plants or leaves. Butterflyfish are sociable and do well in twos or threes, and they are completely peaceful towards other fish of comparable size. They are lovely community fish except for one small thing: Butterflyfish are highly predatory. Since they can only eat fish they can swallow, and since they only reach about 10 to 15 cm in length, they are only a danger to small fish like neons, danios, and guppies. Larger fish, like the bigger barbs and Rainbowfish, silver dollars, gouramis, and angelfish are in no danger at all. You don't need to feed them live fish; Butterflyfish will do well on a mixed diet including bloodworms and mealworms, small insects, and once they're settled in, floating pellets and flake. 

Predatory fish like the Butterflyfish are quite often good community fish once their basic nature is understood. Few of them actually go looking for trouble; pike cichlids, garpike, needlefish, and Colombian shark catfish are all impressive and capable hunters, but they're also good community fish.

2                     Dwarf gourami, Colisa lalia 

The good:            Friendly, colourful, and just the right size for the community tank

The bad:              Peculiarly sensitive to bacterial infections 

Few aquarists haven't tried keeping these fish at some point, and they remain staples of the hobby thanks to their wide availability, bright colours, sweet dispositions, and willingness to take a range of foods including flake and pellets. Numerous artificial forms exist, such as the 'red dwarf gourami' that lacks the blue strips typical of the wild morph. However, being widely sold doesn't mean that are easy to keep, and these fish all too frequently sicken and die within a few months of being purchased. Dwarf gouramis appear to be among the fish most likely to contract bacterial infections if water quality or water chemistry isn't exactly right. The symptoms are bloody sores on the body and a loss of appetite, and short of veterinarian help (i.e., antibiotics), nothing much seems to help. 

Even with antibiotics, the prognosis isn't particularly good, and you should definitely never buy dwarf gouramis from a tank containing specimens showing any signs of this type of infection. But even starting off with healthy fish might not help, as some aquarists believe that virtually all commercially-bred dwarf gouramis (and probably other gouramis as well) carry the bacteria, so the issue isn't keeping the bacteria out of the tank but making sure it doesn't become a problem. The best approach is to quarantine dwarf gouramis for a few weeks before being adding them to a tank that already contains other, hardier, gouramis. 

It is just as important to make sure that water conditions and filtration are optimal. For the dwarf gourami that means soft, acidic water conditions, preferably filtered through peat and zero levels of nitrite and ammonium. Frequent water changes to keep the nitrates down is a good idea, and using a hood or cover glass at the top of the tank to keep the humidity of the air just above the water level high is also to be recommended. Feeding presents few problems, but what you don't want to do is introduce anything that might make the fish sick, such as live Tubifex worms. In short, these are quite demanding fish that need a lot of care if they are to succeed in a community tank.

1                     Black mollies, Poecilia hybrids 

The good:            Hardy, friendly fish full of charm, they even eat algae!

The bad:              Needs hard, alkaline water 

Top of my list of almost perfect fish has to be the black molly. It's a spectacular fish when kept in a planted tank, the velvety black making a bold contrast with the green leaves. Even with more brightly coloured fish, it holds its own, and makes a superb companion for things like fancy platies and swordtails. Few other freshwater fish are as jet black as these mollies, and most of them are nocturnal. Even cichlids keepers -- usually spoiled for choice when it comes to colours -- don't have anything like the black molly; it's a truly unique fish. Like people, the physically most attractive fish aren't always the ones with the nicest personalities, but the black molly is every bit as friendly as it is beautiful. They won't even harm livebearer fry. Despite their peaceable natures mollies are remarkably bold, and will settle into a new aquarium almost at once, making them great dither fish for encouraging more nervous fish like cichlids and gouramis to come out from their hiding places. It gets even better -- mollies are very tolerant of nitrites, making them an excellent choice for maturing new tanks. Provided you don't overfeed them, they'll handle the entire filter maturation process without any problems; they are particularly valued in this regard by marine aquarists who use them instead of more delicate (and expensive) reef species. The icing on the cake is that mollies are fond of algae, and will happily graze on any green and thread algae in the aquarium. While certainly not in the same league as Plecs or Siamese algae eaters (Crossocheilus siamensis), they do have an impact, and are especially good at cleaning delicate leaves where the larger, clumsier species can't reach. 

Really, the only shortcoming to the black molly is its need for hard, alkaline water. Of course, this isn't really a problem for aquarists in the South East, and is in fact something of a plus. Unlike all those neons and dwarf cichlids that demand soft and acidic water to do well, here's one fish that just loves standard issue London tap water. However, if you are keeping a soft water aquarium or have a planted tank with CO₂ fertilisation, chances are the hardness and pH will be too low for the black molly. Ideally, this molly wants a pH of at least 7.5 and the water does need to be at least moderately hard. The addition of salt isn't strictly necessary, but many people have found that it does help to keep mollies healthy and free of diseases like fungus and fin-rot; in this case, raising the specific gravity to around 1.002-1.005 will do the trick nicely and allow you to mix in a few brackish water fish as well. 

To conclude: the black molly is a great fish with which to end this look at the needs of even 'common' community fish. We've looked at five different fish with five distinct issues for the aquarist to tackle: the need for live or frozen food; poor health on import; a predatory nature; sensitivity to illnesses; and demands for a certain set of water chemistry parameters. All five of the fish we've seen here are widely sold as ordinary community fish, but as you can see that doesn't mean you can just chuck them into a fish tank and hope for the best. Other fish may be even more demanding, like discus, Tanganyikan cichlids, or brackish water fish. These present the aquarist with a whole bunch of demands that will need to be met if they are to survive. But it's worth it -- people keep 'difficult' fish because they pay back the diligent fishkeeper in spades when it comes to colour, behaviour, and entertainment value. So, to paraphrase JFK, don't ask what the fish can do for you, but what you can do for the fish!