Wednesday, 7 November 2012

Exodon Paradoxus Fish

Strength in Numbers

Various sources of information on the Internet declare that bucktooth tetras must be kept in schools of ten or more to prevent them from killing one another, but I have found this to be a little far-fetched. I have maintained two separate groups of E. paradoxus at different times, one being six individuals, the other being only three individuals.

I did not have any deaths from the bucktooth tetras picking on one another, but I believe my success was based on the fact that when I purchased these groups, I made sure that they were all identical in size. I also had many hiding places in the form of driftwood and slate and ample floating plants so the bucktooth tetras could get away from one another if they wished.

If one observes a tank with multiple E. paradoxus at an aquatics store, the smaller individuals usually have subdued coloring and are trying to hide, and the largest individuals are trying to chase after anything in their path. That is why I opted for medium-sized individuals that were almost identical in size the two times I purchased bucktooth tetras in groups. Although they do constantly squabble with one another, I never have had problems with major injuries or death.

It is important to realize, though, that larger individuals will often harass smaller ones to the point of death by not allowing the smaller ones to eat and relentlessly chasing them each and every time they emerge from a hiding place. If one does decide to acquire a group of bucktooth tetras, I would still advise having a spare quarantine or hospital tank on hand just in case a situation arises where specimens must be removed due to aggression. This aspect is also particularly important if an aquarist is considering adding E. paradoxus to a tank with other species.

Tankmates: A Tricky Situation


Some aquarists do not necessarily like the idea of devoting an entire medium- to large-sized aquarium to one species of fish, but this is essential for E. paradoxus. I am a cichlid lover at heart, but even the most aggressive Central and South American cichlids that are similarly sized to E. paradoxus often do not fare well in the same quarters.

Bucktooth tetras are so aggressive that most cichlids will simply hide or hang near the bottom of the aquarium to avoid crossing paths, and many times when the cichlid decides to enter the middle or top of the water column, E. paradoxus will knock scales off the broad side of the cichlid's body for a quick snack.

I had a 75-gallon aquarium at one point with three cichlids in the 4- to 5-inch range, the most aggressive of which was a 4-inch Midas cichlid (Amphilophus citrinellus). The other two cichlids were a pair of Hypsophrys nicaraguensis. Within less than a week of adding a group of three E. paradoxus that were each 3 inches long, the cichlids were hiding in the lower level of the aquarium.

The three bucktooth tetras were patrolling the tank as if they owned it, and each time an E. paradoxus would swim near a hiding place, the various cichlids would lunge with flared gills.

Within a couple of weeks, I had decided to remove the two H. nicaraguensis because they were demonstrating breeding behaviors and I did not think that their eggs or fry would stand a chance with the other rough inhabitants. Although they were acting as if they were ready to lay eggs, the H. nicaraguensis still appeared mildly stressed. They were breathing heavier than usual and were also missing some scales, compliments of the three E. paradaxus.

The move left the Midas cichlid alone with the three bucktooth tetras, but it also gave these inhabitants more space. To his credit, the A. citrinellus never backed down. Each time he would emerge from his favorite cave, his fins would stand erect and his gills would flare to threaten the three E. paradoxus. But in reality, the threat posture of fins standing on edge only made a larger target for the super-fast bucktooth tetras to pick off scales.

For months, the three E. paradoxus had perfect fins with no signs of bodily injury, but I began to worry when the A. citrinellus reached 7 1/2 inches and the E. paradoxus were only about 4 inches.

At this time, the A. citrinellus was nearly double the length of the three E. paradoxus

and had substantially more body mass. I just had the feeling that one good bite from the A. citrinellus could mean disaster. Sure enough, while I was observing the tank, one of E. paradoxus bit a scale off the A. citrinellus and as the scale was sinking, the E. paradoxus went after his snack.

Only this time, the A. citrinellus followed his dislodged scale toward the bottom of the tank, and as the F paradoxus swooped in for the scaly snack, the A, citrinellus violently bit off nearly half of the tail of the E. paradoxas. It was at this point that I decided to remove the three bucktooth tetras and give them to a friend who had an open tank.

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