Aqua One Holiday Fish Food Block w/ Suction Cups 2 x 35g (95012) Aqua One Holiday Fish Food Block is suitable for goldfish and tropical fish in 50-60L tanks. It can be placed in both aquariums and ponds and will help feed your fish while you're away for upto week (depends on amount of fish) Do not overfeed your fish before you go away. Perform a 25% water change upon your return with an Aqua One Vac-A-Tank (sold separately) selfstartinggravel cleaner to aid in removing harmful waste from your aquarium gravel. To safeguard your fish from unsafe chlorine, chloramine and heavy metals in tap water when refillingyour aquarium, use Aqua One’s Water Conditioner (sold separately) to maintain a safe environment foryour fish.