The Lemon Tetra, Hyphessobrycon pulchripinnis - An In Depth Primer

I was originally going to re-post the Lemon Tetra article from the days before the 'Year Zero' archiving, but I thought it would be more fun to write a completely new article! So, here is your in-depth guide to the wonderful world of the Lemon Tetra.

One. Basic Preamble.

The Lemon Tetra, Hyphessobrycon pulchripinnis, is, in prime condition, a once-seen never-forgotten fish. How many bright yellow freshwater fishes do you know? Not many, I'll bet. Another feature that stands out, manifested in some other Tetra species, but especially well in the Lemon Tetra, is the intense, iridescent red upper half of the eye. Upon close examination of a prime specimen, the lower half of the eye will be seen to be yellow, with little red speckles covering the yellow base colour. Pectorals are translucent, sometimes with a yellow tint, pelvic fins in fine specimens are yellow, with a black line along the trailing edge. Dorsal is patterned with a conspicuous black-and-yellow flag-like marking, the anal fin has several of the foremost rays an intense, almost acrylic-airbrushed sunshine yellow, with a black band of variable width running along the fin margin (the size of this band is a gender determinant: see below). In especially fine specimens, the tail takes on a sort of gunmetal-blue wash, with some rays notcieably dark. In prime condition, a fish of distinction. Size is frequently quoted as 5cm, though they'll need to be reared in relatively spacious quarters to reach this size.

As an Amazonian species, one naturally expects the Lemon Tetra to prefer soft, slightly acidic water. However, the species exhibits an excellent level of hardiness, which has been enhanced by a long history of aquarium domestication, aided by its willingness to breed. Temperature range is quoted in most books as 21°C to 27°C, but mine have survived a high of 32°C and a low of 19°C during their seven-year tenure in my aquarium, the former temperature being the result of the infamous 2003 heatwave that saw UK temperatures hit a true recorded 101°F for the first time ever. Provided that ridiculous extremes are avoided, pH and hardness ranges are pretty wide, but the optimum for this species would be of the order of pH 6.6, hardness anywhere below 10°dH. Some aquarists contend that this is a fish that benefits from the use of peat filtration, though this is, with a fish as hardy as this, primarily a matter of preference on the part of the aquarist, and those for whom peat filtration is a kind of magic touchstone will find that Lemon Tetras accommodate such measures quite happily.

Lemon Tetras will accept the usual run of aquarium fare with eagerness and relish, but to see them colour up at their best, try the following régime after acquiring them. Intersperse live foods such as Daphnia and Bloodworm (Lemons will go absolutely nuts over live food) with a high-quality colour enhancing flake. Do this for around six weeks or so. At the end of this period, they should be a truly awesome solid yellow. Even if live food is difficult to come by, it is well worth the effort with this species. The colour transformation will be astonishing. Even though Lemons possess a natural translucency of the body, six weeks on live foods and colour flake will turn them into bursts of sunshine with fins.

Two. Points To Look For.

Aquarium furnishings make a huge difference to the appearance of this fish. See a collection of juveniles in a bare dealer aquarium, and one can be forgiven for passing them by and ignoring them. Under those conditions, few fish will have a chance to shine. Do not be put off by this: instead, look closely and see if they are active, perky, and carrying the unpaired fins erect, but not so erect as to appear as if they've had an electric shock! Avoid clamped fins and a listless disposition, as Lemons displaying these are probably suffering from disease. Also avoid at all costs any whose irises look dull grey, or whose red upper half is cloudy: good, healthy Lemons have an upper iris that looks as if it's been carved from a piece of ruby, with a crystalline quality to it. A dull or cloudy iris again more than hints at bad health, and possibly something terminal.

Don't even try obtaining a set number of males and females at this point. Gender separation in juveniles is nigh on impossible by visual inspection alone. Plus, in a dealer tank with 40 or 50 specimens darting about, you'll develop a facial tic trying! Instead, purchase a good sized group (six minimum, twelve much better, and if you have the space to let 20-30 of these fish loose in a well-planned aquarium, be astounded at the results!), and settle them in.

Three. Settling In.

Lemon Tetras are among those fishes that not only look far better in a decent sized shoal (and need the security of numerous conspecific companions, as in the wild, they shoal in groups numbering many thousands), but only truly show their best in an aquarium furnished with at least some sensitivity to their needs. Give them plants - carefully arranged thickets - interspersed with open swimming space. If the aquarium has bogwood decorations, complete with lush growths of Java Moss and Java Fern, for example, so much the better. It doesn't really matter, unless one is aiming for a strict Amazonian biotope, what kind of plants the Lemons have as company, so long as they have plants, arranged so as to provide the combination of hiding places and open water which they like. The difference in their appearance when given a sensitively planted aquarium is, quite literally, stunning to behold. Those washed-out juveniles will start to colour up very nicely indeed. Apply the live food and colour flake régime cited above in combination with a well-planned home, and you'll have Lemons whose colour will start to compete with that of Centropyge flavissimus marine Angels. I'm not kidding: my specimens are a lovely solid yellow of the kind that most dealers can't even dream of replicating. Here's a link to a photo of one of my Lemons that more or less says it all:

One of my own Lemon Tetras circa 1999

Four. Companions.

Lemon Tetras are as adaptable with respect to community aquarium companions as they are to water conditions. They will coexist happily with other Characins (particularly ones chosen with contrasting colour schemes), most small Barbs, Danios, Rasboras, Corydoras catfishes, the usual gamut of stereotypical 'community' fishes, provided of course that these are happy in the same water conditions. They'll also coexist, space permitting, with the likes of Apistogramma Dwarf Cichlids (some of which wild Lemon Tetras share their native waters with), and get on very well with peaceful Cichlids such as Flag Cichlids and Anomalochromis thomasi. It should be stating the banally obvious that they will not last long if dropped in with large Oscars, which will treat them as lunch! Most sensible choices of aquarium companion should work well. Personally, I would exercise caution with freshwater Angelfishes: the Lemons will be too big to eat, but they have a lively and sometimes boisterous nature that might intimidate young Angels, and cause older, larger Angels to become twitchy and trigger-happy temper wise. While they are not considered notorious fin-nippers, care should be exercised vis-a-vis long-finned companions such as male Bettas, and they should be watched for any signs of developing a less than healthy interest in the fin-nipping sport. Most don't, but it pays to be vigilant.

Five. Behavioural Quirks.

This is where my seven years' worth of watching these fish in action comes into play, because you will not see this mentioned in any of the textbooks!

Lemons are among those shoaling Characins that exhibit a behaviour I've labelled 'part time territoriality'. Much of the time, they will crowd together, particularly if there is something like a Blue Gourami in the aquarium with them, and behave like the archetypal shoaling Characin. However, once adulthood is attained, something else manifests itself.

Males begin looking around the aquarium for 'landmarks', from which they can display to each other. Having settled upon their chosen display sites, they start doing just that: displaying to each other. This inevitably leads to 'jousting' incidents. To the unaided eye, it looks as if the Lemons are picking fights with each other. Closer examination will reveal, however, that any 'punches' are definitely pulled. Two well-grown males will approach, head to tail, and adopt a head-upwards posture, spreading the fins as wide as they can, in order to look as big and strong as possible. Once seen, the posture is instantly recognised. Suddenly, one of the adversaries will make a darting pass at the other. No actual contact is made, but quick vision is needed to register this fact. Sometimes, two equally matched males will make repeated passes at each other in quick succession, then resume the head-up 'challenge' posture, and this can continue for as long as half an hour with well-conditioned males ready for spawning. This appears to be principally for the males' benefit, a case of letting off steam and indulging in some ego-boosting macho posturing, because females seem to take little interest in these proceedings. If the females do take an interest, then they hide it well!

Several other Characin species engage in this kind of behaviour, although the details differ from species to species: the common factor is that males pick 'landmarks', display from them, then engage in ritualised contests. Silver Tip Tetras are particularly good at showing this (I kept these as a teenager), but the most extreme example I've encountered (and described at length elsewhere) is the Beckford's Pencil Fish. However, check out any Characin species with a body morphology similar to that of the Lemons, particularly species whose males have tall or prominently marked dorsal fins, such as Black Phantoms and Rosies. The details will differ (for example, when I've seen Black Phantom males squaring up to each other, their orientation has been horizontal), but they'll be as boisterous as the Lemons. Well-conditioned Lemons can be vigorous and enthusiastic pursuers of this particular sport, and the signs should be noted, then watched for.

And, having covered this difference in behaviour between males and females, it's time to cover gender differences of the visual kind. Which, will not make themselves readily apparent until the fish are pretty close to adulthood. The prime diagnostic feature, once Lemons are matured, is this: look at the black band on the anal fin. The female will have her anal fin edged with a fine black line, almost as if drawn with a fine-pointed eyeliner pencil. That of the male, by contrast, will be a thick band, and in prime alpha males will occupy a third of the entire depth of the anal fin. Once seen, it's easily picked up on, but the first time you try, it'll be quite an eye test, because chances are, like me, you'll try this too early in the game. Patience is needed with this. Once your Lemons are old enough, however, the difference will be, in some cases, starkly apparent. A secondary, but less reliable, gender separator is the dorsal fin. Males tend to have taller dorsals, with higher contrast between the black and yellow markings, but this is not 100% reliable, while the anal fin margin width is. Plus, a ripe female with eggs is pretty unmistakable once seen: female Lemons with a big egg clutch can look seriously pregnant.

Six. Spawning.

Key points to note about Lemon Tetra breeding are these. First, live food conditions them for spawning at an astonishing rate of knots. Drop live Daphnia in every day for a week with adult Lemons, and chances are they'll spawn with no other encouragement. Second, morning sunshine is a definite and well-documented spawning stimulus among Lemons. If you're serious about breeding them, put the breeding aquarium in a location where it will receive morning sunshine. Third, when breeding starts, the run-up to the actual spawning consists of chase sequences conducted at breakneck speed. If you have never seen Lemons in the mood for spawning, then be warned, they can dash around the aquarium like lightning! Fourth, they are egg-eaters with a vengeance. More on that later.

Interspersed with the chase sequences just cited, if more than one male is present, will be yet more instances of the 'jousting' described above. When a male approaches a ripe female with that glint in his eyes, however, the signs are manifestly different. First, the 'invitation posture' adopted by the male, when trying to entice the female into some bushy plants to spawn, is head-down. Second, the body is quivered and twitched in a characteristic motion that transmits, to the human eye at least, the male's eagerness to spawn very effectively indeed! Third, the fins are not carried fully erect as 'battle standards', as they are when two males are facing off. Instead, the male will 'flick' his fins, flashing the high-contrast black-and-yellow markings, almost a kind of semaphore signalling to the female.

When a ripe female is ready, and accepts the invitation, into some bushy plants they go. If Java Moss is present in their breeding aquarium, they will use that very readily indeed. The pair will adopt a close, intimate syide-by-side position, and quiver together for a couple of seconds, in a motion that in a flight of fancy I'm tempted to think of as 'scratching itchy bottoms'! Suddenly, eggs and milt will be released. At the moment of release, the pair will jerk away from each other violently - indeed, the parting motion can be so abrupt as to look as if someone's separated them with an explosive charge!

At this point, the infamous egg-eating instinct will kick in. Why? Simple. In the wild, Lemons are 'gang spawners'. One small stream can play host to 10,000 spawning pairs in one go. A large ripe female can produce as many as 400 eggs. The strategy is simple: swamp the area with eggs, so that any egg thieves among the other organisms in the stream are full to burping long before they've made even a tiny dent in the numbers. However, this means that any given pair of Lemon Tetras is faced with a lot of competition for its offpsring, from the potential offspring of all those other spawning pairs. How do they deal with this? A little sly caviar snack on the opposition's eggs does the trick nicely. Reduce the competition, add to the likelihood of your eggs making it through to the next generation. Sounds wonderfully mercenary, doesn't it? That's Nature red in tooth and claw for you.

But of course, in your breeding aquarium, you only have the one pair, or perhaps two if you have two ripe females and two particularly fine males ready for action. Trouble is, the same instinct kicks in. Hunt down the eggs of the opposition. Only there is no opposition. So they end up eating their own. And they are very efficient at this. So, if a decent number of baby Lemon Tetras is the desired end result, ingenuity is called for. Time to devise an egg trap. Several designs exist, all of them work reasonably well, and in the case of Lemons, any reasonably competent egg trap design is a must, otherwise most of the spawn will end up in the parents' stomachs.

For a spawning medium, give the parent Lemons bushy foliage. Cabomba is a good choice, Java Moss is excellent, but if live plants of the right kind (fine-leaved foliage) are not available, nylon spawning mops will serve the purpose just as well. The books usually cite 27°C as the spawning temperature, but Lemons are as adaptable in this respect as in many others: I've seen them spawn at 24°C, and at 32°C. However, 27°C is probably the temperature to aim for, though I wouldn't worry unduly if your aquarium heater doesn't remain nailed to this figure with surgical precision.

At least one book (my Braz Wakler pocket book) states that two males with one female may yield better results. This is, presumably, because first timers in particular might be a little slow getting into gear, so to speak. More experienced males with several prior spawns will probably do fine alone with the female, but if fertilisation rates turn out to be disappointing, this tip is worth noting.

One final point: parents can sometimes spread spawning over 2 or 3 days. During this time, the books usually say that they should not be fed. This one puzzles me a bit - I'd have thought that adding some Daphnia would take their minds off hunting for their eggs, but this is an experiment I've yet to try. Perhaps it'll bring the spawning to an abrupt halt too, which is what youdon't want. Those with an experimental streak, try this out, see what effect it has, and if it ruins the spawning, then we'll all know why the books tell us not to do it, although if this is the case, why do none of them actually say so explicitly?

Seven. Raising The Fry.

Now for the fun part. Before embarking upon a breeding spree, some jars will be needed. Jars in which pieces of lettuce, boiled peas etc., will be rotting away nicely underwater. The reason? Infusoria.

Baby Lemons need infusoria for the first 7 days of their lives. You could try raising them entirely on liquid fry food, but I suspect the results would be a lot better with at least some live infusoria added to the baby feed mix. And, because of the aforementioned fertility of the female, there will be a fair number of babies to feed. Even given the parental instinct for caviar, a good egg trap might save 90% of the eggs if you're lucky, in which case you will have over 300 baby Lemons begging to be fed. And they will eat at a surprising rate.

So, you'll need to set up infusoria cultures. And stagger them. So that you have a 7 day supply of little food organisms for the baby Lemons. If you have any snails in any of your aquaria, pop them into the cultures too, because snail droppings are, apparently, a wonderful accelerator for such cultures. Wait for the cloudiness to be replaced by the appearance of lots of little specks hopping about in the water. These are your infusorians. Prime baby fish food. And they will be snapped up eagerly by your Lemon Tetra fry.

After 7 days, it's time to try newly hatched Brine Shrimp. And think about segregating for size, and, unless you have a large nursery waiting for them, the not so happy business of deciding which ones go on to be raised for the pet shop, and which end up being fed to your Convict Cichlids. Because 300 baby fish will place a BIG demand on nursery aquarium space. Better to raise 30 bouncing juveniles than 300 stunted runts, unless you have a 6ft aquarium doing nothing into which you can place them. And, once they're on newly hatched Brine Shrimp, growth will be pretty fast.

And, finally, a little experiment. Instead of taking them to the pet shop for sale as juveniles, hang on to them for a little longer, colour them up yourself, and then take them down. Chances are your pet shop will be so used to seeing pale, insipid Lemons, that if you present a bunch of solid yellow ones that radiate with colour, you'll be paid more.

Eight. Final Words.

I've had Lemon Tetras for seven years. They are perky, fun, sometimes rather boisterous but otherwise good-natured Tetras that get along well with a wide range of other aquarium companions, and if given decent levels of TLC, transform ugly-duckling-into-swan-style from the typical pale dealer fish to lovely solid yellow gems that will have quite a few people asking "Just how did you get your Lemons to be so yellow ?" Hardy, dependable, and surprisingly long lived - two of my males are from the original batch, and still going strong seven years down the line - Lemons are frequently overlooked because they aren't given a chance to shine in bare dealer aquaria. Give them that chance to shine, and they will - resplendently!