Salty Q&A: To Rinse or not to Rinse Frozen Foods?

Rinsing frozen aquarium food


This is probably a silly question, but should I rinse frozen food before feeding it to my fish? I usually just thaw the food in a cup full of aquarium water and pour it right in.” – Submitted by GMan


Here at Saltwater Smarts, the only silly question is the one left unasked (well, that and “What can I take to cure my kleptomania?”). Besides, I’m sure plenty of other folks out there are wondering the same thing.

As is so often the case with questions pertaining to this hobby of ours, my answer is, “It depends.” Many frozen foods contain a lot of packing juice (you’ll see a cloud of the stuff in the water right after feeding) that will serve only to introduce dissolved nutrients, degrade water quality, and fuel algal blooms. So I will usually strain and rinse them in a fine-mesh net before feeding.

Typically I do this over the sink under a stream of RO/DI water, but you can also put the portion in a cup with a little water, wait a few minutes for it to thaw, and then, with the net held over the sink, pour the contents of the cup through the mesh. After rinsing/straining and while the food is still in the net over the sink, I also like to apply a little gentle pressure (not squashing it) to the portion with the back of a spoon in order to squeeze out as much extra fluid as possible.

However, there are circumstances in which you might not want to strain/rinse frozen foods. One example is when the food consists of or contains items of a very small particle size that you don’t want to risk losing down the drain. In this type of scenario, what I usually do is thaw the portion in a small bowl placed in the refrigerator. After thawing, I tip the bowl while applying gentle pressure to the food with the back of a spoon in order to drain out as much of the packing liquid as possible. I then soak up any excess juice that drains toward the edge of the bowl with a small section of paper towel before feeding.

Another instance in which straining/rinsing may be unnecessary is when the frozen food in question comes pre-rinsed and is already pretty “clean” right out of the package. I’ve found that to be the case with LRS Reef Frenzy®, which I simply thaw in a small volume of aquarium water before feeding.

I’m sure other salties out there have additional thoughts on whether “to rinse or not to rinse” frozen foods. If so, perhaps they can be persuaded to share them in the comment section below.


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About Jeff Kurtz

Jeff Kurtz is the Co-founder/Editor of Saltwater Smarts, former Senior Consulting Editor for Tropical Fish Hobbyist Magazine, and the aquarist formerly known as “The Salt Creep.” He has been an aquarium hobbyist for over 30 years and is an avid scuba diver.


  1. The amount of liquid waste (if we can call it that as I am far from sure it goes to waste) in frozen food with the likes of phosphate in it is minimal, just a drop in the ocean. There are articles on the web (not sure if I can put links to them here) giving in depth details of the amount of phosphate you are likely to be adding to your tank which in truth is not worth bothering about. I don;t filter. strain or do anything with the liquid in my frozen foods, many of which I make myself, other than dump it in my tank anlong with the food. Also there is more than just phosphate in this liquid that will help feed some filter feeders.

  2. I always strain things like Mysis or any other commercial food except clams. Clams, when thawed exude juice but that juice is used by corals so I add that to the water. If I am hungry, and I have enough, I make myself a plate of linguini and clams out of it.

  3. I never add Mysis because it is to hard to de-vein and de-shell them

  4. Most of my frozen food is the San Francisco Bay brand and, according to the package (and their website), it’s not necessary to thaw it before feeding…just drop the cube and go. To this point, I haven’t had any issues with my fish and eating it straight from the cube. Hikari cubes say the same thing…

    I used to thaw it out in tank water until I saw on the package that it was unnecessary…

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