The pharmaceutical industry may be able to obtain bioactive metabolites from macroalgae for use in developing new drugs. It is a plentiful supply of all necessary nutrients and shows promise as a source of pharmacognosical value. Alkaloids, phenols, flavonoids, saponins, steroids, and associated active metabolites are of high medicinal value and are frequently used in the pharmaceutical and medical fields. The aqueous extracts of Padina tetrastromatica phytochemical components were investigated. The qualitative examination found alkaloids, steroids, tannin, phenols, saponins, terpenoids, and flavonoids to be present. Traditional antibiotics are becoming less effective in the present environment of rising and emerging drug resistance in a variety of microbial diseases, so research worldwide has concentrated on generating alternative therapy treatments with effective microbe abilities. The results of this investigation showed that extracts from the seaweed Padina tetrastromatica could be a possible replacement for the creation of bioactive leads in the treatment of aquaculture A. hydrophila infections.