ExampleNavigation.js

const ConversationsStack = createStackNavigator(
  {
    ...
    Conversations: ConversationsScreen,
    ...
  },
  {
    ...
    navigationOptions: ({ navigation: { state: { index, routes } } }) => {
      return {
        tabBarVisible: true,
        tabBarLabel: () => <Text style={styles.tabBarLabelStyle}>{t('tab.messages')}</Text>,
        tabBarIcon: ({ focused }) => <TabBarIcon focused={focused} name="message-processing" />
      }
    }
  }
)

const MainTabsScreens = createMaterialTopTabNavigator(
  {
    ConversationsStack,
  },
  {
    tabBarPosition: 'bottom',
    tabBarOptions: {
      showIcon: true,
      style: {
        backgroundColor: 'red'
      }
    }
  }
)