Is the thick white fluid that is discharged during strong arousal and erection considered maniyy (seminal fluid)? And does its discharge nullify ghusl (ritual bath) and fasting, or only wudu' (ablution)?

The clear, viscous fluid that is discharged when thinking about or being aroused by lust is called madhy (pre-seminal fluid). It is impure (najis) and nullifies ablution (wudu'). It is obligatory to wash the penis and any clothes that it has touched. However, it does not necessitate the major ritual bath (ghusl) and, according to the more correct opinion, it does not invalidate fasting even if discharged through mere looking.