"Lydia" wrote in message
...
One of my two lamp eye tetras is doing something odd. It just
constantly
swims up. If he stops swimming he sinks like a rock, but it never
stops
swimming straight up long enough to sink all the way to the bottom to
just
lay/rest there. It's like he's swimming head first into a strong
current...
constantly. He's eating and otherwise looks normal. Has been going on
for
about a week and no other fish in the tank are doing this.

Is there anything I can do for him?

Thanks for the help,
Lydia

Fish regulate air in and out of an organ called a swim bladder. This
organ sits in the mid-point of their body's weight, slightly higher up
towards their dorsal fin. This organ usually works to keep their total
weight to be the same as the water (ie: tetras), so if they stop all
motion with their fins, they will just hang in the water, not sinking or
floating to the top. With catfish, it keeps them heavier. With
Hatchetfish, it keeps them lighter. Whenever fish eat, the swim bladder
has to adjust according to what was swallowed. Some fish have more
trouble with this than others. If the swim bladder is set to low in
their body, then any swallowed air will cause them to flip around and
swim upside down for a while (ie: goldfish). Tiger barbs tend to drop
their nose lower than their tails after a meal.

In the case of your Lampeye, the swimbladder's ability to regulate itself
is gone, and the fish doesn't have enough air inside, so the fish drops
to the bottom. It doesn't understand this, so it swims to the top,
before sinking again. How long it will live, whether it's contagious
etc, depends on the cause of the illness. Mechanical injury might repair
itself, organ failure or internal bacterial infection will probably not.

In nature, he would be eaten at the first sign of distress. In an
aquarium, it all depends on who he has for company. You can quarantine
him and if curious, add a bit of Epson salt into the water. A possible
course of action is antibiotics, but that's not practical or economical
for single small fish. Maybe it is just getting old.

NetMax