Sure. I used the bbp_new_topic_pre_content Filter Hook and the code I used is as under:
 //code to limit number of characters in topic contents to 500 characters
 
function tm_limit_topic_content( $topic_content )
{
    /* Check for number of characters in topic contents  */
    if (strlen($topic_content) > 500) {
		$revised_content = substr($topic_content, 0, 500);
		}	
	else {
		$revised_content = $topic_content ;
	}		
 
    return $revised_content ;
}
 
add_filter( 'bbp_new_topic_pre_content', 'tm_limit_topic_content' );
		
	 
	
	
	
 
		
			
	
	
		
		Never mind. After some trial and error, I have been able to find out the relevant filter hook and achieved the goal. Thanks.