There are several Antivirus applications available for android online. And my recommendation is to go for Netqin Antivirus software which is great in mobile security & to maintain the good performance of your phone.
Netqin mobile antivirus is well known for it's protection and performance. This antivirus not only protect your phone from threads online and offline, it also maintains your smartphone's' "performance" & your personal data with many tests like Battery, RAM, Phone Memory, Message, Contacts, etc. You can backup your data on their free cloud storage. It is also available in other OS' like Symbian. You can get the trial version of the software from play store and have look at the performance and protection provided by "Netqin antivirus" and check whether it fits on your mobile or not. Netqin also comes with different themes which is pretty in look. You can also contact their support centre, if you having any problems.
Here is the download link to Netqin Mobile Antivirus for Android
And it's not a must to install a antivirus software on your smartphone unless you are changing your storage devices with friends or coworkers. So, if you want protection plus phone's long lasting performance then you can simply go for Netqin mobile security/i>.
Thanks & Regards,
All I Can Do Is Be Me!