Question about guppies...

Question
I just started a 75 gallon tank about 2 weeks ago.  After letting it sit for a few days we got four tetras.  Then a week later got 4 Tequilla Guppies.  The guppies have been strange since we got them.  They swim up and down the side of thw tank--should I be concerned?  Why would this be?  I know they like plants and I have a lot of plants (fake) in the tank.  Do they make some kind of floating plant?  Would this be beneficial to them?

Thanks!!

Answer
Hi Kim!

~You shouldn't have anything to worry about... Many species of fish will do this kind of behavior and the most likely cause is the fish sees his/her own reflection in the glass and wants to 'follow that fish wherever he goes' it sounds silly but it's true. Territorial fish such as some cichlids including Oscars repeatedly swam up and down and side to side in an attempt to get to reach their imaginary rival and fight. I also believe when fish are newly introduced to a tank, they spend quite some time getting to know their new boundaries by exploring as many nooks and crannies they can--- and by swimming up and down the tank to see what their limits are of their new aquarium.
I have had many fish show this behavior quite often, peaceful or territorial species... But eventually after some time my fish whether it's a peaceful platy or an Aggressive Oscar, they will eventually either lose interest in their imaginary rival or friend and go about other natural behaviors, though they may repeat this behavior every so often, it shouldn't become excessive.

Guppies LOVE plants, I believe all fish do! Though live plants are most preferable, live plants can also be a trouble to maintain and keep healthy, requiring special light levels and specific water conditions. But there are species that can be maintained in most average tanks, if you would like a list of common and easy live plants you may want to keep in your tank --- just ask.
Otherwise, Guppies will do just fine with fake plants as well. They prefer their plants to be grouped in bushy bunches where they can hide if they feel insecure about their surroudings. You can find specially made floating plants that often look very realistic and make a perfect secure habitat for small fish like guppies, and if you have females, their babies will love to hide in large groups of floating plants and will increase their chances of surviving by escaping possible predators like your tetras and  guppies.

I hope this helped! Congrats on your new 75 gallon aquarium! I wish you the best with everything!

If you have anymore questions, feel free to email me!

Happy fishkeeping!
Karen~