How to avoid/overcome animations on bottom navigation bar on android

Question

The navigation bar has 4 buttons, all of color gray. Each one inflates a specific fragment. when clicked on it,it changes its color to red.

The button which is clicked is also becoming larger(bigger).I want to change the color(gray to red) but not size. How to achieve this (not changing the size of button)?

Thanks in advance.

The following is the part of the code:

Menu xml:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/navigation_home"
        android:icon="@drawable/ic_feed"
        android:title=""/>
    <item
        android:id="@+id/navigation_dashboard"
        android:icon="@drawable/ic_analytics"
        android:title="" />
    <item
        android:id="@+id/navigation_profile"
        android:icon="@drawable/ic_profile"
        android:title="" />
    <item
        android:id="@+id/navigation_settings"
        android:icon="@drawable/ic_settings"
        android:title="" />
</menu>

kotlin code:

private lateinit var bottomnav : BottomNavigationView
val navUtils = NavigationUtils()
private val mOnNavigationItemSelectedListener = 
BottomNavigationView.OnNavigationItemSelectedListener { item ->

    when (item.itemId) {
        R.id.navigation_home -> {
            val locationhistoryinstance = 
            LocationHistoryFragment.newInstance()
            loadFragment(locationhistoryinstance)
            setTitle("Calender Test")
            return@OnNavigationItemSelectedListener true
        }

        R.id.navigation_dashboard -> {
            val analyticsinstance = AnalyticsPageFragment.newInstance()
            loadFragment(analyticsinstance)
            setTitle("Analytics")
            return@OnNavigationItemSelectedListener true
        }

        R.id.navigation_profile -> {
            val profileinstance = ProfileFragment.newInstance()
            loadFragment(profileinstance)
            setTitle("Profile")
            return@OnNavigationItemSelectedListener true
        }
        R.id.navigation_settings -> {
            val settingsinstance = SettingsFragment.newInstance()
            loadFragment(settingsinstance)
            setTitle("Settings")
            return@OnNavigationItemSelectedListener true
        }
    }
    false
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_home)
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener)
    bottomnav = findViewById(R.id.navigation)

    navUtils.disableShiftMode(bottomnav)

}