Aggression in Congo Tetras 7/9/07
Greetings, Crew!
I wish this site had been available to me 35 years ago, when I first started keeping fish...this is hands-down, the most helpful source of aquatic information that I have found. Thanks for all your caring and hard work! I've been a long-time "lurker", but this is my first time asking a question.
I had a group of six Congo Tetras that I purchased locally about four years ago. They were juveniles when I bought them; it turned out that I had two females and four males.
<Greetings! Congo tetras are among my favourites.>
Everything seemed fine until recently, when I lost the females and one of the males over the span of about a month. There would be a "sudden death"...no warning, no strange behavior, water parameters were stable, and right on.
(125 gal tank, Eheim 2028 canister filter plus a Tetra 60 hang-on, plus the weekly use of a Vortex diatom; ph 6.8, temp. 78, ammonia and nitrates 0, nitrate 5.0 or under.
<Interesting. Conditions sound perfect.>
Mixed fake and real plants, driftwood, sand, gravel and pea-gravel substrate.
Tank inhabitants: 6 giant danios, 7 red serpae tetras, 6 glowlight tetras, 7 red-tailed rasboras, 1- 4" pleco, 3- 3" clown loaches, 1- 6" striped Raphael cat (he's been with me for at least 6 years), 2- 8" banded Leporinus and most recently, 3 koi angel fish that were about the size of a quarter, but are about double that now.
<Some "courageous" choices as we say in England. Angels and Serpae tetras are usually a VERY bad combo, because Serpae tetras nip slow fish with long fins, and Angels are slow fish with long fins. Leporinus fasciatus are famous for being aggressive and having huge teeth that can shred pretty well anything. I have known experienced aquarists who describe them simply as "evil"!>
Quarantine tank used religiously, water changes of about 20% twice a week. Foods are various Tetra brand flake and granular, Spectrum pellets, peas and frozen blood worms)
<All sounds very good.>
After the first Congo turned up dead, I started to watch the tank dynamics more closely. There has always been a good bit of excitement around feeding time, but the Congos were actually beating each other to death!
About a half-hour after feeding, the Congos would start displaying and slamming into each other, sometimes so violently that there would be scales knocked free. None of the other species of fish took part, or were targeted by the Congos.
<Well, the obvious thing to do would be remove some of the males and add more females. A school of 6-8 specimens should work, and certainly did for me.>
I'm now down to the remaining three males, and it seems that they have come to a truce...I've seen no more violent behavior.
I would like to add a few more of these beautiful fish, but I'm hesitant to do so, fearing that the new ones may suffer the same fate, or that the new introductions may spur a whole new round of violence.
<The best solution might be to re-home the 3 you have, at least temporarily, add 6 more Congo tetras, and once they're settled in and sufficiently large, add the other 3 back.>
Can you offer any insight? I've done some researching of these fish, and don't find any mention of this belligerent behavior.
Thank you.
Tracy G.
<The social dynamics of schooling fish can be very variable, and I've seen similar things to this in a variety of supposedly schooling fish, from danios to archerfish. Generally, the bigger the group, the less problematic, so adding more will be your best chance of fixing things. To some degree, all schooling fish use bullying to establish a hierarchy. I'm watching the Asian glassfish in my aquarium here right now, and these fish are constantly dive-bombing one another. While this adds to the fun-value of schooling fish, if the numbers are too small this jostling of position can lead to damage or death, as you've discovered. Adding 6 more Congo tetras should be fine, as the three left will not be able to harass these too much. Since you have a big tank, adding more fish shouldn't overwhelm the filter. Good luck! Neale>

TigerFish (HYDROCYNUS VITTATUS)
Dear Bob
I would like to enquire about a market for live tiger fish.
Is there a market for live tiger fish?
<Yes, but a limited one... do to their size, voraciousness, and difficulty in shipping (they don't move well)>
Who would be the best candidates to purchase live tiger fish?
Could you let me know if it is possible to export live tiger fish to the USA?
<If I were a supplier, I'd try various freshwater wholesalers... or if you just wanted to sell to one, contact Steve Lundblad at Dolphin International (Los Angeles) re>
Would it be possible to give me a couple of names of live fish distributors in the east (Japan, Taiwan, Thailand, China)?
<Please see the O.F.I.s listing here>
I heard from someone that there was a big market for these live tiger fish in the east, but after searching far and wide, I have not been able to get any detail ...
Please can you help?
Freddie
<I don't think this market is large... I would look into selling at least other African species as well... Bob Fenner>