A third-party FBReader port is available on Tizen Store (in Educational apps category). The port is based on the original C++ code and supports ePub and fb2 (including fb2.zip) formats. Network catalogues are not supported yet, as well as synchronisation.
The app works on Samsung Z1, Z2, and Z3 devices with Tizen 2.4. For more details please contact Alexander Kryzhanovsky, the developer of the port.
The port sources are available from Github under the GPL.
You can also simply change the font size, or switсh the reading mode day / night.
More settings are available in 'Preference'.