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.>