How territorial are established fish?

[sinistral]

Hi all,

I have my 29 gallon tank set up since 12/15/03. Cycled, ammonia, nitrites = 0, pH 7.6, fake plants and 5 lovely platies.

After doing quite a bit of research I have decided to make community tank with four different schools (platies, glowlights, black neons, bronze cory cats). I'm planning to add fish over the next few months, probably not more than 21 fish total based on their size and stress to my filter. Yesterday I went to my LFS and got a school of 6 glowlights. My original plan had been to get 4, but the glowlights were on the small side and I suspected my tank could take the addition to the bioload.

The platies have been bullying the newcomers incessantly since I added them. They chase them around, nip at their fins, and won't leave them alone unless the glowlights hide in the plants or beside the airstone, for example.

Is this normal behavior? After I got through fretting and wringing my hands I called the LFS and the manager said that old fish are often territorial when new fish are introduced. He suggested I wait 2 or 3 days as long as the glowlights aren't being bitten to pieces, and to turn off the tank lights (which I had already done). I'm concerned that the platies are more interested in eating the glowlights rather than bullying them. Any suggestions?

Thanks so much~

 

[gadazobe]

I doubt if the platties will eat the glowlights, just harrass them. Make sure that there are plenty of hidey places for them to shelter, keep the lights off for a couple of days and things should settle down by then. The platties have had control of the tank since they were introduced to it and they object to sharing their "territory" with others, but once they realize that they're not in danger, they should calm down.

 

[Changes-In-Latitude]

You could rearrange the tank decor. This sometimes helps with territory problems.

 

[sinistral]

Wow...thanks gadazobe and Changes-in-Latitude for the quick responses! I will keep the lights off for a few days then, or until the harrassment stops. I added a new plant to the decor for shelter as I was adding the glowlights; I would say the tank is moderately decorated with 8 plastic plants, a big rainbow rock, a small rainbow rock, and a small lava rock. Maybe I will try to rearrange the decor, as I've been thinking about doing it anyways...

EDIT: Just got home this afternoon to find all 6 glowlights shoaling peacefully near the plant cover, and the platies ignoring them completely. Thanks for the help!

 

[Changes-In-Latitude]

Cool, always like a story with a happy ending