Fish Seem to Like "Cooked" Algae

TwoTankAmin · May 23, 2026

One of the issues many of us face with planted tanks is that they grow. I have a lot of anubias that have grown to the surface of tanks between 18 and 24 inches deep. As they get nearer to reaching the surface they are getting ever closer to the light. At this stage they are way more subject to getting algae, often this is more than one type which often includes BBA. As far as I can tell the only solution for this problem is to pull the plants, bleach dip them and return them to the tank. Ultimately I will chop off the top 1/3 of an anubias and make it a new plant. Often I have no room for put it anywhere else and I sell it. Sometimes I will even sell the whole plant to open up more open swimming space for the fish.

If you have ever done this you should have noticed that there is no immediate change in the appearance of the algae soon after the dip and returning the plants to their tanks. But the algae is actually dying but has not showed this yet. But in the next 24 - 36 hours what happens is the algae loses its color and it turns a white or grayish color. For some reason it strikes me as having been cooked by the bleach.

What is even more interesting is how much my fish and shrimp like to eat this "cooked" algae. If there were no fish or shrimp present, that whitened algae will gradually vanish on its own. But, with living critters, it becomes a feast.

I am wondering if anybody else has seen this if you bleach dip plants as described above? The fish and shrimp are eating dead algae and it got that way by being "cooked" by the bleach, IMO.

anewbie · May 23, 2026

I've always been reluctant to bleach dip as I'm 'worried' that bits of bleach will remain and slowly poison my fish

Naughts · May 23, 2026

I used to take out driftwood and pour just boiled water on it to kill the green algae. Neocardinia would then clean off every last bit of the dead algae, yet they had never made a dint in it when it was alive. I guessed the hot water softened the algae which made it more palatable?

jaylach · May 24, 2026

I've never seen this but will just throw out a guess...

Yes, in a way, the bleach is cooking the algae... sort of. You can 'cook' shrimp in strong lemon juice due to the citric acid in the lemon. Sounds good but there is a basic problem. Citric acid can 'cook' but bleach is about as far from acidic being a strong base biased on the actual PH level... whatever, it isn't acidic.

Still, since bleach will kill the stuff, there is a change in the algae due to the bleach so we know there is an intake, or method, for the bleach to get in the algae. We know the algae reacts to the bleach; Yes, I consider dying a reaction.

My deduction, valid or not, is that the bleach alters the algae at least on a cellular level.

As to why the fish like it I don't have a clue but it would seem fair to assume that the change in the algae either adds a nutrient they want or it just makes it taste good.

Just, please, remember that this post is just guessing and speculation.

TwoTankAmin · May 24, 2026

A little research showed me that the cooking veggies in a higher pH causes them to become more tender. One the other hand a low pH will help preserve crispness. One thing about bleach dipping plants. They do not show the signs of dying right away. It is at least not until the following day that the algae is looking white. Clearly, the bleaching makes them more tender and easier to eat. I have no idea what the dip does in terms of the nutritional values involved.

In poking around on Google about using bleach on plants it came back with a few words of advice from the AI.

Key Details on Using Dechlorinator for Bleach:

How it Works: Dechlorinators, such as Seachem Prime, contain agents like sodium thiosulfate that break down chlorine instantly upon contact.
Application: For cleaning items, soak them in a water-dechlorinator mix for 15–20 minutes after rinsing off the bleach.
Safety Measure: If bleach is added to a tank by accident, you can add an overdose of declorinator to neutralize it.
Best Practice: Ensure the bleach used does not contain fragrances or other additives. Rinsing thoroughly and allowing items to air dry completely is also effective as chlorine will evaporate.

How can dechlor break down chlorine instantly on contact followed by advice to cleave the dipped plants in the dechlors for 15-20 minutes? The source given for all of the above is Reddit. I cannot imagine a worse place to go to get for accurate information except maybe for Youtube. The problem hare is what it says for Application is inaccurate. I have been bleach dipping algae covered plants for almost as long as I have kept plants in tanks. I have them in the strong dechlor bucket for about a minute. The plants may be parked in a plain water container before they go back into tanks. But that is because I will bleach a few plants one after the other and want to return them all at the same time. Often, the plants will come out of the dechlor bucket and go directly into their tank.

I tend to use Prime for this. It says to add a cap full for 50 Gallons. I add that cap full to a dechlor bucket with fewer than 5 gallons of my well water which contains 0 chlorine or chloramine.

This is why one should never trust the Google search AI for anything unless you are using it to save time in writing and you know what the AI states to be true before you even asked Google. If you are not sure, look at the source of the answer Google provides. When they give a scientific answer from a source which is not at all science related, be very careful. When I want to know the science I tend to use Google Scholar which searches only for scientific literature- papers, books, dissertations and articles.

anewbie · May 24, 2026

TwoTankAmin said:
A little research showed me that the cooking veggies in a higher pH causes them to become more tender. One the other hand a low pH will help preserve crispness. One thing about bleach dipping plants. They do not show the signs of dying right away. It is at least not until the following day that the algae is looking white. Clearly, the bleaching makes them more tender and easier to eat. I have no idea what the dip does in terms of the nutritional values involved.

In poking around on Google about using bleach on plants it came back with a few words of advice from the AI.

How can dechlor break down chlorine instantly on contact followed by advice to cleave the dipped plants in the dechlors for 15-20 minutes? The source given for all of the above is Reddit. I cannot imagine a worse place to go to get for accurate information except maybe for Youtube. The problem hare is what it says for Application is inaccurate. I have been bleach dipping algae covered plants for almost as long as I have kept plants in tanks. I have them in the strong dechlor bucket for about a minute. The plants may be parked in a plain water container before they go back into tanks. But that is because I will bleach a few plants one after the other and want to return them all at the same time. Often, the plants will come out of the dechlor bucket and go directly into their tank.

I tend to use Prime for this. It says to add a cap full for 50 Gallons. I add that cap full to a dechlor bucket with fewer than 5 gallons of my well water which contains 0 chlorine or chloramine.

This is why one should never trust the Google search AI for anything unless you are using it to save time in writing and you know what the AI states to be true before you even asked Google. If you are not sure, look at the source of the answer Google provides. When they give a scientific answer from a source which is not at all science related, be very careful. When I want to know the science I tend to use Google Scholar which searches only for scientific literature- papers, books, dissertations and articles.

It isn't horrible advice - you might not need to leave it in there for 20 minutes but it won't hut anything. I'm more concern when 'AI' answers tell you to do something 90% or 180% incorrectly.

sharonmartinxo · Wednesday at 11:46 PM

That makes sense to me. Bleach kills and breaks down the algae, which may explain why the shrimp suddenly love it.
The “cooked algae” effect is pretty interesting! I also agree that AI search answers should always be checked against reliable sources.

gimme30 · Friday at 4:23 AM

I've been doing hydrogen peroxide spot treatments on some stubborn BBA that the amanos won't touch....until it's "cooked," and then they clean it right up.