The invention describes novel preparations and their use for reducing the acute damaging effect of ammonia in organisms living in the keeping water of aquariums, garden ponds, or aquaculture systems. The preparations consist of adducts of sodium hydrogen sulfite at an aliphatic aldehyde of the general formulaX—(CH2)n—CO—H,whereinn means the numbers 0 to 3, andX means an —OH, —COOH, or —CO—H group,wherein X cannot be —OH, if n=0. The preparations are used in the keeping water with a concentration of 10 to 140 mg/l.
