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FAQs on the Serpae Tetras

Related Articles: Cardinal Tetras; A School of Beauty, Part II,  by Alesia Benedict, Characid Fishes

Related FAQs:  Cardinal Tetras, Characid/Tetra Fishes,


Tetra sudden illness        3/4/19
We’ve a 29 gal tank we clean & test weekly. Normal ranges. 5 Serpae tetras, 3 other tetras (silver?) a loach and a Pleco. been with us 2+ years with no problems. Everyone ELSE is fine.
Between yesterday morning roll call and today’s, this Serpae tetra went ghost pale, floating weird a la swim bladder, and I think he/she looks bloated. Wedged itself into plant leaves. And stopped moving & swimming. Infrequent breathing.
Any ideas on illness?
<Hard to say. Small tetras sometimes contract diseases that are all very similar in appearance (lethargy, loss of colour, disinterest in food, perhaps social behaviour oddities like leaving the group and hiding instead). In some cases they are bacterial, in others microbes of other types, like Pleistophora. In all honesty, with these very small fishes, it's often best to simply euthanise to reduce the risk of cross-infection. Clove Oil does the job nicely.
Serpae Tetras are generally very tough, legendarily so, though they are also notoriously nippy towards other fish and aggressive towards their own kind, especially when feeding. There are some lookalike species (such as Ember Tetras) that aren't nearly so tough, and don't handle hard water (for example) as long as Serpae Tetras. So I'd keep an open mind in that direction, too. Cheers, Neale.>

Minor Serpae Tetra fin rot?     11/2/14
Greetings. I have a 55-gallon aquarium that we set up 2 years ago & has been stable and disease-free. Water parameters are: ammonia = 0, nitrite = 0, nitrate = 30, phosphorous = 0. I do a water change every week. We have live plants (water sprite wisteria). The inhabitants are 2 Bristlenose Plecos, 8 black-skirt tetras, 8 white-skirt tetras, 11 minor Serpae tetras, and about 6 apple snails. The Serpae tetras were introduced about 2 weeks ago and my quarantine tank currently is housing some baby Gold Gouramis, so
I chose not to quarantine them. I know I should have, but I have never had any problem with the tetras from this source. A bad decision on my part, but anyway, may I explain the problem to you...?
<Fire away.>
Oddly enough, the other fish in the tank seem to be still healthy and unaffected by this disease bothering the serape tetras. It is the strangest thing I have ever seen. The first sign is a very pale area where the dorsal
fin meets their body. It's very clearly delineated and easy to see against their red-orange background. Soon after that, the dorsal fin degenerates and the fish seems to die within a day or two after they reach that stage.
They don't seem swollen and neither do they show any other signs of illness. I have never seen fin rot behave like this or fin rot that just affects one species of tetra. Today, I got some API Triple Sulfa and am
planning on giving them the entire course of treatment as directed by the manufacturer. Do you think that I am on the right track here? Please advise and thank you so much for your time and any comments you may have for me.
<Serpae Tetras are notorious fin-nippers, so one explanation is that they're fighting within the group (which they do, especially when feeding) and damaging one another. When feeding they have a feeding frenzy
behaviour, but will also bully weaker specimens, even killing them. Usually they attack other fish too, but the Black/White Skirt Tetras (both Gymnocorymbus ternetzi) are pretty pushy, fast-moving little fish
themselves, and may be holding their own just fine. Gouramis, though, are easy targets so I wouldn't mix them. This said, it is rare for Finrot to kill fish within a couple days. Adding more Serpae tetras might help, by
spreading out any aggression, but before doing that you'd want to observe the Serpae Tetras and see if they're chasing or nipping each other. If they are fighting, adding a few more could be a good move. Alternatively, you might simply have a "bad batch" of Serpae Tetras, in which case medicating for Finrot might stabilise things, giving you time to see if they can be saved. If the fish get better, then no harm done. If they eventually all die, I'd recommend not buying Serpae Tetras again. Although cheap and usually extremely hardy, they aren't well behaved fish, and there are better alternatives such as Red Phantom Tetras out there.>
<Cheers, Neale.>
Re: Minor Serpae Tetra fin rot?    11/15/14

Greetings. Well, I treated the entire aquarium with API Triple Sulfa for four days and then observed the aquarium for several days and the mysterious problem of the bacterial infection with the Serpae Tetras seems to have been eradicated. All the fish look very healthy.
I have been watching them closely for fin nipping and have only seen a limited amount of chasing amongst the Serpaes and a few isolated incidents of them bothering the black & white skirt tetras who, as you previously
stated, can give it back to them even better than the Serpaes can dish it out.
<Often the case. Both species are "fin nippers" but Serpae Tetras tend to be more persistent and vicious, whereas Black Widows generally behave themselves if there's enough of them.>
I haven't seen them bothering the gold gouramis, who can be rather pugnacious also if they choose to do so.
<Males, yes; females less so, if at all. Also, as they age, they slow down a lot, making them easier targets, so do keep an eye out for them.>
I will watch the gouramis closely and move them to another aquarium if necessary. I will keep watching the Serpaes for aggression. I have not found anyone yet who has any idea exactly what this strange infection was,
but the guy at PetSmart said that the others that came in in that particular group had to be treated with antibiotics as well. Anyway, just to let you know what the outcome was with this incident. Thanks for the heads-up on Serpae aggression. I did notice that they are on nippy fish.net where they seem to be known as the culprit in many a fin-nipping incident.
<Indeed. Excellent fish in terms of colour, size, and usually hardiness.
They were extremely common fish in the aquarium hobby during its earlier phase. But nowadays are not as popular. Unfortunately some retailers give them alternate names, making it easy to buy them by mistake. Red Minor Tetra, Jewel Tetra, Hyphessobrycon eques, Hyphessobrycon calistus and Hyphessobrycon serpae are some of the names you'll see.>
Thanks again for your advice.
<Welcome. Neale.>

How small can I go? 12/3/10
Hey gang, looking for help picking a freshwater fish. I would like to set up a tank of schooling predators, active, swarming, shiny, greedy little fish. The challenge that I'm setting for myself is a using a very small
tank. Probably a salt water style Nano tank, (primarily for aesthetic reasons), I'm thinking 14-20 gallons. Can you recommend such a fish? I have already ruled out Exodon paradoxus as probably to big (am I wrong?).
Thanks for being awesome
<Your best bet would be Serpae Tetras. These have a true "feeding frenzy" behaviour which is why they can create such mayhem in community tanks. Keep at least eight specimens, and preferably one per gallon of water, with 15 gallons being the minimum tank size. These fish are insanely nippy sometimes, and will bit chunks out of each other at feeding time. They were the first fish I ever kept, and in part the subject of my first ever TFH Magazine article on ten fish aquarists shouldn't keep. But I suspect you'll find them just the thing. They're hardy, nicely coloured, and look amazing in tanks with lots of Java moss and Java ferns, which shouldn't be hard to do in a small tank. Exodon paradoxus is a great fish, but you do need much
more than 20 gallons for them, realistically, 55 gallons would be about right for a school of ten, which is the smallest number at which they won't eat each other. Cheers, Neale.>
Re: How small can I go? 12/9/10

Thanks man, very helpful. My LFS guy, offered Aphyocharax paraguayensis as a solution as well. Do you know anything about them? Seems to be little info.
As always thanks very much.
Warm regards,
<Hello Rob. Aphyocharax paraguayensis isn't much traded, particularly when compared to the very popular (and hardy) Bloodfin Tetra, Aphyocharax anisitsi. Compared to the common Bloodfin, Aphyocharax paraguayensis is a little over half the size (3-4 cm) but otherwise pretty similar in terms of care and personality. It's a peaceful schooling fish, but nippy, so best kept with species able to avoid fin-nippers (i.e., not angels, fancy guppies, Bettas, Corydoras, etc.). Water chemistry should be soft to
moderately hard, acidic to neutral, and the water turnover rate should be fairly brisk as these are active swimmers, so aim for turnover rates from 4-6 times the volume of the tank per hour. Cheers, Neale.>

Serpae tetras - Neale's Recent Post   2/9/10
I'd like to thank Neale for mentioning the trouble with these demon fish.
<Oh! Another "once bitten, twice shy" story, I suspect!>
I had done my research but unfortunately there are plenty of big sites that will lead you astray on this fish.
I worked up to 7 of these fish as per other sites. More in the school less likely for trouble.
<Is (usually) true with Tiger barbs, where the nipping is more about frustrated social behaviour than anything else. But Serpae tetras and their close kin are fin-eaters in the wild, and they view fins the same way puffers view snails: potential meals!>
What I got after adding some peppered Cory catfish was nothing I've read anywhere else. The tetras really attacked their fins and what was most disturbing was that the tetras would lie in wait. They would often hover at 90 degree angle to the catfish waiting for the right moment to strike.
<Oh yes. These fish have evolved to feed on fins, and this stealthy behaviour is precisely what they do.>
The cats would be on the bottom of tank doing what they do. I'm not talking about a nip as the catfish would intrude on the space of the tetras. I mean a deliberate wait to attack regardless of where the victim was.
<To be fair, Corydoras are fairly stupid fish that don't seem to learn anything. Which is why they're so often bullied (supposedly even blinded) by dwarf cichlids. They never cotton on to parts of the tank being off-limits, so keep blundering into trouble. By contrast, I have some Dwarf Synodontis in a pufferfish aquarium, and they quickly learned to keep a low profile!>
The other thing they would do is "head butt" the catfish as they came down from getting breath at the top of the tank. Never on the way up but always on the way down.
This would have made good video to show how evil these fish can be but I had to separate them before causing any more harm. The cats simply had lost spirit and would only come out when they had to and race back to the bottom in order to be safe.
<Yes, this is how bullied Corydoras behave. Wild Corydoras are said to be nocturnal, and they will revert to that behaviour if the aquarium isn't peaceful.>
Petco a large chain here does warn that these fish can be nippers.
PetSmart the other huge chain does not. They list them as community fish on their tanks.
Even my LFS hadn't heard of tetras behaving this badly. I'd like to see these fish de-listed from the community categories at the retailers.
<Up to a point, I agree. While hardy and very pretty, it's a difficult fish. One problem is that there are multiple Hyphessobrycon of similar appearance, and some are perfectly peaceful while others are nippy. So on the one hand you have the Flame Tetra (Hyphessobrycon flammeus) which is shy, even timid, and on the other hand the Common Serpae (Hyphessobrycon eques), a very vicious little nipper! I suspect that some reports that Serpae tetras are "community fish" come down to misidentifications. Again, we come to this issue with common names rather than Latin names being used too loosely.>
I would also like to see when recommendations for a particular tetra be made, that this fish be specifically mentioned as one that should be kept on their own.
<Well, Serpae tetras can be superb fish *on their own* in things like Amano-type tanks, where their small size, bright colours, and schooling behaviour can work well. On the other hand, there are many other tetras I'd recommend ahead of them for community tanks. Among the best are things like Pristella Tetras in terms of hardiness, Bleeding Heart tetras as companions for medium sized fish, and Congo tetras where you're after show-stopping fish that grab the eye.>
Anyway, thanks Neale for spreading the truth on this fish.
<Thanks for writing! Cheers, Neale.>

Attacked female guppy... Serpae Tetras   2/5/10
Hello, I have a 30 gallon tank with a large variety of fish. I have to female guppies who are always swimming around untill recently they have been hiding In the temple for a few days. This morning I was looking for them and one was finally out and I shook the temple to check on the other one. He came out but his fancy tail Is almost all the way chewed off..
Could this be from the other female because I don't have any males? The only new fish I have Introduced them to are three white clouds, Three tetra Longfin seep, and three tetra bloodfins. Are any of these to aggressive for
the guppies?
<What's with the bizarre use of capitalised "I" all over the place? Is this some new thing teenagers do to annoy people? In any case, the Serpae tetras are almost certainly to blame here. Serpae tetras are notorious fin nippers. The fact you're keeping both Minnows, Serpae and Bloodfin tetras in groups of less than 6 specimens makes things even worse. Out of frustration, any one of these species could go rogue. Do read on the needs of fish prior to purchase. Cheers, Neale.>

Re: attacked female guppy -- 2/5/10
Ok thank you.. My spell check must have made the caps. The people at Petco said three of each would be fine.
<Ignorance on their part, and a reminder why you should read about a fish before buying it.>
Do you recommend getting rid of the guppies or getting more Serpae tetras?
I noticed there are a few red eyes nipped also.
<Serpae tetras will nip everything given the chance, including each other (long-finned versions usually look very raggedy). So while colourful and extremely hardy, I find them rather useless fish. Cheers, Neale.>

Are there such a thing as serpae tetra subspecies? 05/25/09
Hi all,
Firstly thanks for all the help with the SAP, plus the website is amazing!  I just picked up another serpae tetra today (I miscounted the last time and
only had 11) so the total is now up to 12. This new tetra looks identical to the other 11 tetras in the school--except s/he is lacking the black dot located behind the eye. At first I thought it was stress-related but the fish has adapted well and is eating... but no spot.  Is there such a thing as subspecies?
<The "subspecies" concept does indeed exist, humans for example being a subspecies of Homo sapiens, Homo sapiens compared with Neanderthal Man, Homo sapiens neanderthalensis.>
The 11 Serpaes look like this:
And the new serpae looks like this:
<The problem here is that what the industry calls "Serpae Tetras" can be any one of multiple closely related species in the genus Hyphessobrycon.
While Hyphessobrycon eques is probably the most commonly traded member of the Serpae Tetra Species Complex, other species of Hyphessobrycon may be traded periodically as well. Even within Hyphessobrycon eques there is substantial variation between geographical populations, and artificial varieties further muddy the waters. The absence of the black spot above the shoulder (called a humeral spot) could easily be explained by any of these reasons. This variation has probably meant that what people report when keeping "Serpae Tetras" has been very variable over the years. True Serpae Tetras -- Hyphessobrycon eques -- are noted for being aggressive feeders and have a feeding frenzy behaviour very similar to that of large, predatory characins such as Piranhas and Exodon paradoxus. They are also distinctly nippy, and will take bites at slow-moving fish such as Corydoras, Platies, Angelfish, Guppies and so on. Personally, I do not recommend them as community fish at all. In fact they were my first ever tropical fish, and the species with which I learned not to trust without verification anything the pet show owner said! After I added some Angelfish and Gouramis to my tank, I was shocked to see the carnage, and from that point onwards have been much more critical about the information casually

Weird behavior? (Serpae Tetras, no surprises)  -- 10/23/08
I am a new to this hobby. I have a 30 gal hex tank with a heater (78 degrees) and bio filter. Listening to the guys in the aquarium store I cycled my tank using a male Guppy and two Sunset variatus (one male one female). Everything was going great, and finally after one month I got my water tested by the store and they said I could add more fish. They suggested another male guppy and three Serpae Tetras.
<Bad community fish; Hyphessobrycon "serpae" (in fact a variety of Hyphessobrycon species is a known fin-nipper. They are schooling fish that need to be kept in groups of at least six and realistically 12+. They have a feeding frenzy behaviour, and will attack anything in range when feeding, including each other. Bullying is a problem with this species. Under no circumstances should this species EVER be added to community tanks with slow or long finned species such as Guppies.>
From the moment I added the new fish my original Guppy began to act strange. What once used to be an active fish swimming all over the tank turned into shy fish hiding in the plants (fake). The new male Guppy seems to be bullying all the other fish (including the Serpae Tetras who I thought were supposed to be more aggressive).
<Male Guppies will certainly be aggressive towards other male livebearers (such as Platies) given the chance. All livebearers should be kept in groups of one male to every two or more females to reduce this problem. I heartily recommend against keeping different livebearer species because of differences in behaviour and aggression level.>
This morning (the morning after I added new fish) my original Guppy's tail fin is about half the size.
<Attacked by the tetras.>
He is laying on the ground and only moved to get food and then returned to the ground not moving at all. What is going on? Will my fish die? What can I do?
<Obviously the Serpae tetras must go. Please read an aquarium book BEFORE purchasing new fish. The fact these are [a] nippy and [b] schooling fish is no unknown and will be revealed by any decent aquarium book. I happen to like (and rate highly) Baensch's Aquarium Atlas, but there are lots of others.>
Thanks in advance for your help,
<Cheers, Neale.>

Fish inquiry... Tetra, small Characin sel., comp.   7/15/08 Dear Crew, I'm pretty new to the fish keeping hobby but I have been researching online. Here is my dilemma. I have a tank with serpae tetras who keep to themselves (thank god), zebra Danios, a rubber lip Pleco, and platys. <A "courageous" combination to say the least. Serpae tetras aren't my recommendation for the community tank, as you seem to realise.> I need a somewhat larger fish to be the so-called "attraction" fish but I don't know which kinds will live peacefully with my other fish. <With Serpae tetras, not much! The obvious choices -- Angelfish, Gouramis, etc. -- will simply be pecked to death.> I have a 26 gallon tank, its pretty tall and its a bowfront. I've been deciding between some kind(s) of gouramis, freshwater angels, or silver dollars. <No, no and no respectively. The Gouramis and Angels will be nibbled to pieces, and the Silver Dollars get far too large for a tank this size.> Which species is best suited for my tank and well get along with the tankmates; and if you have any other suggestions about other species please let me know. <To be honest, I'd not bother. I'd either up the numbers of the species you already have, or perhaps add an interesting catfish of some sort that can keep out of trouble. Serpae tetras for example look their best in big swarms of dozens of specimens, when their feeding frenzy behaviour becomes quite something to watch. Of course any catfish that avoids trouble, like a Synodontis, isn't going to be showpiece fish you're after.> Also, ever since I transferred a red wag platy over to the bigger tank, it has constantly been hiding even though none of the other fish harass it. <Almost certainly it has been nipped by the Serpae tetras and is keeping a low profile. Serpae tetras don't just bite the fins from other fish but also the scales, and such damage can be difficult to see.> Is there any way I can solve this problem? <Not really, no.> Thank you, Pierre <Hope this helps, Neale.>

Re: fish inquiry  7/15/08 Thank you for that info. Do you think there are any tetras that I could replace the Serpaes with that would get along with angels or gouramis? I might decide to take them back to the pet store. Pierre <Angelfish will simply view very small tetras, such as Neons, as food, so you have to be careful. Certain other tetras, can be just as nippy as Serpae tetras and will nibble on the Angels and Gouramis. Black Widows (Gymnocorymbus ternetzi) and some of the other Hyphessobrycon species fall into this category. My honest recommendation would be to replace the Serpae tetras with more Zebra Danios. Here's the thing: if you have one big school of a schooling fish, it looks so much better than two small schools of different schooling fish. You would then have one species at the top (the Danios), one in the middle (perhaps a pair of Angels or a pair of Lace Gouramis) and then your catfish at the bottom. Instead of a jumble, you'll have an nice ordered arrangement. Otherwise, consider X-Ray tetras (Pristella maxillaris), Diamond tetras (Moenkhausia pittieri), or Lemon tetras (Hyphessobrycon pulchripinnis) are excellent community tank tetras and the right size for your aquarium. But as I say, better to have twelve schooling fish of one type than six of two different types. Cheers, Neale.>

Re: fish inquiry (Dwarf Gouramis, Angelfish, selection)   7/15/08 I'm going to exchange my Serpaes this evening. I think I will most likely go with the large school or Danios and either dwarf gouramis or angelfish. I'll let my little brother pick. Thanks so much for all your help! Pierre <My advise to anyone is don't get Dwarf Gouramis (Colisa lalia, including fancy forms like "neon gouramis", "robin gouramis", and so on). Unless wild-caught or locally bred, which the ones in shops most certainly are not, these fish are extremely likely to carry an incurable viral disease known as Dwarf Gourami Iridovirus. One estimate by vets puts the incidence at 22% for Dwarf Gouramis exported from Singapore. Because the virus is extremely contagious, you only need one infected fish in a batch to ensure all the others get sick too. The number of Dwarf Gourami e-mails we get would astonish you, and they really are a complete waste of money. Almost every retailer I know dislikes stocking them because so many die in their tanks, but there is sufficient demand among newbie aquarists who don't know better that they remain profitable. It's a shame, because twenty years ago they were quite good little fish. Nowadays, you're better off with the hardier (if slightly bigger) Colisa fasciata and Colisa labiosus. http://www.wetwebmedia.com/FWsubwebindex/dwfgdis.htm If you buy Angelfish, do remember these are territorial cichlids. You cannot sex them. But if you have two males, in a small aquarium they are very likely to become aggressive towards one another. If you buy a singleton, then there's an increased chance that Angelfish will "go rogue" and attack other fish in the tank, so that approach is not without risks. The standard way to keep Angels is to buy six specimens, let them pair off as they mature, and remove the four surplus fish when the time comes. Because Angels are such popular fish, rehoming adults is not difficult and any half-decent aquarium shop will take them off your hands. Cheers, Neale.>

Re: fish inquiry (Dwarf Gouramis, Angelfish, selection) 7/17/2008 Can the dwarf Gourami virus spread to other species of fish or only the ones in the Gourami family? <This is a complex question. The short answer is yes, the virus can spread to other species in other families. But so far as I know, the only scientifically documented example is where Dwarf Gouramis Iridovirus appears to have infected Maccullochella peelii, and Australian perch-like fish belonging to the Percichthyidae family. There are no reports that I am aware of where the virus has caused problems in other species of Gourami though. Hence my recommendation that Colisa fasciata and Colisa labiosus are safe, reliable alternatives. Yes, they aren't quite as colourful, but they are still lovely fish and much, much more likely to live long and happy lives. If you want a small, non-aggressive Gourami for the community tank, these are the ones to go for. Cheers, Neale.>

Neon Tetras And Serpae Tetra, incomp.  5/5/08 Hello there, nice to be back! I have my problem with my 9 neon tetras and 5 Serpae Tetras. First week after I buy the Neons the Serpaes are not doing anything to the Neons, they don't disturb them. <Yet...> Yesterday I saw one of my Neons has no tail then one Serpae attack the neon and bite the neon's tail. <Ah, there it is.> I'm shock when I saw it, and until now I can't imagine the worst thing my Serpae did. I think of possible solutions, and it came to my mind that if I remove the Serpae tetra (3 of them) will the aggressiveness will be minimize, I will just remain one male and female. Is it ok? <Nope. Serpae tetras, as I point out repeatedly here at WWM, are not community safe. They eat fins and scales in the wild, and also have a "feeding frenzy" behaviour that means they lunge at anything and everything when feeding. Mixing Serpae tetras with anything other than more Serpae tetras is not a good idea. Period. End of discussion. They're great fish on their own, but were the very first fish I ever kept way back in the early 80s, and I learned my lesson the hard way.> please give me the right solution. My tank is 10 gallons, planted, and an Amazon blackwater layout. <Neons need cooler water (around 22 C) than Serpae tetras (around 25 C), so aren't really compatible anyway. I'd get rid of the Serpae tetras, since a 10 gallon tank is too small for them. Keep the Neons, let the temperature drop, and if you want obtain some suitable tankmates for this sort of tank, e.g., Corydoras habrosus.> Hope you will reply soon. Thanks and more power! <Hope this helps! Neale.>

Serpae Tetra Stopped Eating 4/1/08 Hello Crew, First of all, thanks so much in advance for your help. We are new to the hobby, and are not sure what information you'll need, so have included as much as possible below. We have a 55 gallon freshwater tank; it has been up and running with decorations since December 2007. We are using a Marineland Penguin BioWheel 350 for up to 75 gallons, and have included an Algone pouch in the filter to help control algae. We also have a circulation pump on the opposite side of the aquarium from the filter that has a flow rate of 2300 L/H, 600 GPH. There are no live plants, but there are a lot of silk plants, large pieces of wood, and floating plant decorations, providing plenty of hiding places. The first fish were added on Feb 24: 4 Head and Tail Light Tetras, 4 Red Eye Tetras, and 4 Harlequin Rasboras. During this time, levels of Ammonia and Nitrate stayed at 0, and PH was steady at 7.0; one water change of 15% was performed on March 16, and levels continued to stay the same. Temperature fluctuates slightly between 77 and 79 degrees. On March 22, the following fish were added: 2 Farlowella Catfish, 4 Emerald Green Cory Cats (Brochis Splendens), 4 Serpae Tetras, 4 Black Tetras, 6 Brilliant Rasboras. The Ammonia / Nitrite / PH levels have continued to stay the same, and most of the fish are doing great. Additionally, we have been adding API's Stress Zyme weekly as directed, to help the live bacteria. However, there is one Serpae Tetra that has recently stopped eating (we have been feeding once per day with Aqueon Tropical Flakes, and planned to incorporate other types of food later). At first, all 4 Serpaes ate the food. All the other fish are still very interested in the food each day, and swim freely around the tank, but this particular Serpae stays in one corner of the tank pretty much all the time, and is most often near the bottom. At feeding time, the other fish rush over to the food, but this Serpae stays at the bottom of the tank, usually hiding under a piece of wood. We have not noticed this fish eat for 4 or 5 days. He shows no obvious signs of illness. Two of the other Serpaes have dorsal fins that look as if they could have been nipped, but this Serpae has a perfect dorsal fin. We have not noticed any bullying, although the other three Serpaes do chase one another around, and one of these three (with a possibly nipped fin) often hangs out nearby the non-eating Serpae. How can we get this guy to eat? Thanks, Kate and Jason <Greetings. Serpae tetras (Hyphessobrycon spp.) are not good community fish, and they do indeed feed on the scales and fins of other fish. They will nip other fish in the tank, particularly slow moving things like catfish. Secondly, Serpae tetras have a "feeding frenzy" of sorts, and when kept in too-small a group they are apt to bully one another. Even six specimens is too few to get good behaviour from this species. You need 10-12 at least for them to create a stable "pack". Frankly, I'd recommend against any aquarist keeping them unless they know precisely what they're letting themselves in for. Yes, they're cheap, and yes, they're hardy, and yes, they're pretty. But they just aren't good aquarium fish. Sooner or later you will find your Serpae Tetras bully each other to death until you end up with just the one specimen. Stories of people keeping "peaceful Serpae tetras" usually end up being situations where people have kept look-alike tetras with nicer personalities. Do read up on the species sold as "Serpae tetras" , i.e., Hyphessobrycon callistus, H. eques and others. Remember also to treat nipped fins: these can quickly become infected, yielding to Finrot or Fungus. As a total aside, many of your fish are schooling species: that means they MUST be kept in groups of at least 6 specimens. When kept in too small a group they will, at the least, be stressed. You're also not going to see them behave normally. Resist the temptation to treat them like pick 'n' mix candy and take a couple of these and a couple of those. They're animals, and they have needs. Trust me on this, you'll also find them longer-lived, healthier, and more rewarding when kept in SCHOOLS rather than small numbers. Cheers, Neale.>

Re: Serpae Tetra Stopped Eating 4/1/08 Neale, Thank you very much for your response. We definitely do want to have healthy and happy, non-stressed fish (we thought a group of 4 was good for schooling fish, obviously a mistake). It sounds like we should remove the Serpaes and take them back to the LFS (they are definitely Hyphessobrycon callistus). If we did that and increased the other schooling fish (Harlequin Rasboras, Head and Tail Light Tetras, Red Eye Tetras, Black Tetras, Emerald Cory Cats) to 6 fish, would that be all right, or is that too many fish for our 55 gallon tank? We don't want to overload it, and doing that would remove 4 fish and add 10. Our apologies if this is a naive question--we are beginners and we greatly appreciate your help. Thank you, Kate and Jason <Hello again! Six is generally considered the MINIMUM number for schooling fish. Any fewer and they just don't "school". Upgrading your schools to 6 or more in a 55 gallon tank will be fine. I'd even go for 8-10 a piece. Serpae tetras were the first fish I ever kept, back around 1987. All they did was nip, nip, nip. Terrible fish. What they are is miniature piranhas, and kept on their own in a big swarm they're actually quite good fun. When they feed, they go berserk, and will rip bits off each other if they can't get enough food to eat. It's a real feeding frenzy. But as community tropicals, they are of limited value. Anyway, all your other fish would be fine, except with these provisos: Black tetras (by which I assume you mean Gymnocorymbus ternetzi) are also fin nippers, though usually only when kept with Gouramis, angelfish, guppies, Bettas and the like. With other tetras and fast-moving fish they're fine. Red-Eye tetras (Moenkhausia sanctaefilomenae) are only very rarely reported to be fin-nippers. Keep an eye out for it, but in groups of 6+ they should be fine. Again, don't put temptation in their path. Farlowella catfish are perhaps the most difficult commonly traded catfish to keep alive for any length of time. They are really a fish for advanced hobbyists. The problems are two fold. Firstly, they're easily damaged by other fish (look out for signs of nipping, e.g., damage to their tail fins). Secondly, they are almost entirely algae-eaters, and cannot "scavenge". You will need to add Algae Wafers to the aquarium at least 3-4 nights per week for these fish to eat, though frankly I'd be surprised if the Corydoras didn't eat them first. You can also offer thin slices of softened or blanched vegetables, weighted down with little bits of lead (the stuff used to hold down aquarium plants, very cheap). Courgette (zucchini) is a favourite, but tinned peas, cooked spinach, and Sushi Nori will also be taken. Some small invertebrate foods like bloodworms will need to be give as well. Lifespan in most aquaria is sadly rather short. Hope this helps, Neale.>

Serpae Tetras Badgering Cory Cat   8/1/06
Hi WWM Crew! <<Hi, Stella. Tom here this morning.>> Hope you all are doing well. <<We hope you are, too!>> I have a 10-gallon freshwater aquarium with 5 small serpae tetras, a small bronze Cory and 2 small Otocinclus (everyone's around the same size of "small" except the Cory is more block shaped). <<Sounds fine.>> I introduced the serpae tetras about a week ago and they have been a complete terror with the poor Cory, nipping his dorsal and caudal fin to pieces. <<It would seem that I spoke too soon.>> I was hoping they would eventually adjust to the tank and stop the nipping but they aren't and the Cory isn't able to recover. I've decided to move the Cory to another 10-gallon tank that I have but is currently empty. <<He/she will be happy for the relief, I'm sure.>> My question is whether I should move the Cory before the tank has cycled or wait the 3-4 weeks for the new tank to cycle completely. <<It doesn't sound to me like those juvenile delinquent Tetras are going to leave the Cory alone long enough for the other tank to completely cycle.>>   My current tank is well cycled with no trace of ammonia or nitrites and nearly zero levels of nitrates. <<This is going to help.>> Which is the least of two evils: fin nipping or uncycled tank? <<The fin-nipping is the lesser of the two but five against one are odds that no fish should have to contend with. The Cory's stressed and likely injured (to an extent) which is going to make it a prime target for an infection of some description. That alone would likely mandate the move so let's look at the options. The first I would recommend is doing water changes in the QT with water from the cycled tank. Since we're not dealing with a pathogen issue in the older tank, this shouldn't be a problem and may, in fact, help us along. If you have a source for BIO-Spira (Marineland), you'll be able to eliminate this dilemma altogether but it's not always easy to come by locally. If you have a good fish store nearby, you might give them a call, or visit them, to see if they have this specific product in stock. Beyond these two, the best counsel I can share is to keep an eye on both the Cory and, certainly, on the water conditions until this tank settles out.>> Any advice would be appreciated.   ----Stella <<Wishing you the best of luck here, Stella. Tom>>

Re: Serpae Tetras Badgering Cory Cat - 8/10/2006 Thank you so much for your quick answers, Tom! <<You'll make me blush, Stella! You're very welcome.>> I just wanted to let you know that the Cory is happily swimming about in his very own nearly cycled tank. Doing the water change with water from the already cycled tank really did the trick. <<Neat trick, isn't it? :)>> I will probably get him a companion Cory soon as I've read that they like to be among their own like kind. <<Oh, they don't do bad by themselves, Stella. When you get a chance, post again and I'll give you the brief rundown on "schooling" fish. They don't "school" as much as some would like us to believe... Corys are a good example.>> Sadly, one of the Otocinclus is now getting slightly nipped in the tail as well. Are these serpae tetras just bad seeds, or is there something I should be doing to prevent this behavior? <<Not "bad seeds", just little pains-in-the-butt (if you'll pardon the expression). Pretty fish but are somewhat notorious fin-nippers.>> I've placed a small glass jar in the bottle <<bottom?>> of the tank to serve as an Oto hideout which I think has helped some, and there are a couple of plants (plastic and real) for cover as well. <<Mine have, finally, lost their love of nipping at everything that comes across their "plate". Still rambunctious but not nearly as bad as they used to be. When they discover that your Oto is faster than they are, they should lose interest.>> Thank you for an advice you can give.    ---Stella <<Nice to "talk" to you again, Stella. Tom>>

Fading Serpae Tetra  - 2/15/2006 I recently bought 2 Serpae Tetras about a week ago.  They are in a 10  gallon tank with 2 fancy tail guppies. <Like different water...> All are doing fine, but noticed this  morning one of the Tetras looks like it's fading.  He's not the bright  orange and black he was before.  What do you think could be the  problem?  Thanking you in advance..... Jenny~ <The Tetras "like" soft, acidic, warm water (80's F.), the guppies, hard, alkaline, cooler water... Bob Fenner>

Serpae Tetra shimmy while swimming 8/9/05 I have a ten gallon tank with 3 Serpae Tetras, 2 Platies, and 2 Otocinclus. My tank is 8 months old and I have not had any problems with it other than a rough start with cycling when I first set up the tank and a case of ich (during that cycling period) that wiped out all the fish except one Tetra.  It is that original Tetra that I am having a problem with.  He seems to shimmy when he swims.  I have read all of your postings on "Shimmy"  but they all seem to indicate that the fish is standing still when he shimmies. <Usually, yes>   My fish only shimmies when he is actually swimming.  This started a couple weeks ago and at first I thought it was some kind of mating behavior but now he seems to be swimming slightly slanted to the side.  He still has a healthy appetite and seems to be playful with the other fish.  Any ideas?  Is this something that I should treat.  All the other fish seem fine. Even though this fish survived the start up cycle and the ich could that have had any long term effects on him? Thank for all you do Tina <Thank you for writing, and so well, thoroughly. This one fish sounds like it is neurally damaged... perhaps from the cycling trouble, ich-medicine exposure. It very likely does not have something that is catching. I would just keep it as you have been, and hope it straightens up. Bob Fenner>

School's In Session Long story. I have a 5gal tank, for lack of expenses, though I have heard that 20gal is better. Last week, out of compassion or whatever, I tried to save some goldfish some people on my college campus were not treating right. Oops. Found out later that they are not good starter fish. Well they all died within a few days. I had not given the tank enough time to cycle. I was told that I could get a couple fish to put in here for starters. Three days ago I got one Serpae tetra and one black skirt tetra. The man at the pet shop said they were his favorites to use. Later that day, I found out online about the schooling fish, and that they need to be in groups of six minimum. What do I do? They seem healthy so far, active. <Well, I would give your tank a little more time to finish cycling, then you might want to add maybe two more of each. Not exactly a school, but small groups> I realized yesterday that I was overfeeding, so I have cut back to once a day, smaller pinch. Water is clear, but there is a smell, reminds me of urine. No other way to put it... Here are my questions. is the smell something bad? how do I get rid of it? <Well, if it smells like urine, it may not be a good thing. A healthy tank has an "earthy", pleasant smell, not an ammonia-like smell. What kind of filter are you using? If you are not already (and assuming your filter can accommodate it), try using some activated carbon. That will help remove discoloration and odor. And, of course, in a small tank, you should be diligent about regular water changes! Acquire some test kits: ammonia, nitrite, nitrate. By regular water testing, particularly in the early stages of your tank's existence, you can really get a handle for what's going on.> Would the two groups work good together, or do I need eventually to get a separate tank? <I think that they will work with diligent attention to maintenance, but you will eventually have to get a larger tank to accommodate these fish at full size. Maybe neon tetras would be a better choice for the long run?> To add fish, how big a tank do I need for a good number? <Maybe a 10 or 20 gallon tank. This would give you more flexibility> Don't have the gages yet, but will be getting them soon. Any help will be so appreciated. Thanks for everything. I've been reading and it's good info. Amy <Keep reading and learning! You're doing great! Scott F.>

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