i started with about thirty, a large school to go into a 65 gallon heavily planted aquarium. they pretty much have the tank to themselves, the only other fish in the tank is a single siamese algae eater that i somehow missed. eventually, when the fish are a little fatter, i will try to remove him as well.
ok, so i get the fish, bring them home, and set them up in a ten gallon to observe them. in the crowded ten gallon, which also had about 20 H. formosa and five L. parva, they seemed quite calm. they ate well, didnt pick on each other, and didnt seem to spook easy at all. for th five days i had all these fish in the ten gallon, i only lost three, all of which had injuries that i didnt expect them to survive. the water quality never deteriorated, i was constantly changing water out with the 65 gallon planted, which only had one small fish. plus i used a couple air powered filters i made out of a large pool filter element that i had filled with carbon.
anyway, when i moved the bluefins over to the 65g tank, their behaviour changed. at first, they schooled heavily, all following the largest male. they went from one side to the other, back and forth. this lasted about a day. and then things got weird. i started seeing dead fish, and fish that were just floating upside down gasping for air. sometimes the fish would "snap out of it" and start swimming, most times they would just die.
i tested the water and watched them. i noticed that if i turned the lights of, they would absolutely freak out and dart every direction. a few would slam into the walls and go belly up. so, i had my answere! or so i thought...
i tried leaving the tank on overnight to avoid a sudden light change, but that didnt work either. the next time i added food, i came back within a few minutes to see several more dead fish. they had obviously just died...
i started watching them very closely when i fed them. at first, i just added a frozen bloodworm cube, and and watched three fish promptly kamakaze the walls of the tank. ok, so maybe the cold worms are making them freak out? i tried thawing them first and didnt see any more deaths. great! i had my answere...
Nope.
the next feeding time i thawed the worms out and added them to the tank, and watched yet ANOTHER four fish commit suicide. i had never seen anything quite like this. then i noticed something. three of the four fish this time had a slight amount of blue on their fins. the other looked as though it had red on its tail. (i cant always see red as im colorblind).
as it turned out, only the males were killing themselves. i started changing the way i fed them. i would spread the food out across the entire tank and try to keep the males from having to go to the same area too feed. this seemed to work a little, but they also forage. during the time i was not feeding them, the males seem to find each other, which sends one darting off into oblivion.
in the wild, i guess this wouldnt be a problem. they dart down into the plants and swim at break-neck speeds untill they are safely away from the dominant male. in a large tank, that gives them just enough room to get up to ramming speed.
i havent had any more deaths in about a week, but i also have far fewer males.
this has been an interesting lesson on bluefins for me. as an aquarist, i can tell you that it is very unsettling to watch your fish commit suicide evertime you feed them. it should also serve as a warning to anyone who collects these fish from the wild. try not to get too many males...
and if you are colorblind like me, it helps to have someone who can see red. even if they dont have blue on their fins, they will have red on their tails.
Edited by Auban, 04 July 2012 - 03:31 PM.
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