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Shape of Tank and Substrate for Discus


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Hello, All,

Mark here and this is my first post to the forum.  I’m going to be start a new Discus tank.  This will be first venture into these guys.  I was originally going to put them in my 125 gallon 60” tank with a few angel fish.  Starting off I was going to purchase 5-6 juveniles at once and go from there.  I’ve read through YouTube videos and forums and have found more opinions than are helpful until I stumbled upon Aquarium Co Ops videos.  I have two unanswered questions:

1) how important is the selection of type of substrate with Discus.  It will be a planted tank so I want some substrate.  People say sand is very important, but how important is it really?  White sand gets messy looking real quick.

2) I also have a 60 gallon cube tank.  If I put five discus in there with no other tank mates with a twice a week water change will that work or do they need lateral space to swim?  The cube tank sits in the middle of the living room and would display them more beautifully I think.

Any help would be appreciated.  In advance, thanks and happy fishing!


Edited by Marksm33
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Mark, let’s break the internet together. I keep Discus in a 55 gal. planted tank. First few inches of substrate are Black Diamond Blasting Sand; upper several inches are a cap of Eco Complete. I have a million Malaysian Trumpet Snails. I’ve kept a handful of other tank mates: Tetras, Barbs, Plecos, Acaras, Rams, Apistogramma, and more. I tend to overstock (not recommending, just saying). I only use two large Sponge filters for Filtration, and added airstones in center. I water change 25-50% just once per week. Sometimes I add tannins after a water change (tints water yellow-brown).  Temperature stays warm: 83-87° F. Here are some photos from the last year…





















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First: @Fish Folkis a way better fish keeper than I. 

I have my 5 discus in a 75 with 2 angels, a couple bristlenose plecos and a few cardinal tetras.  I keep the water around 83, and (keeping in the internet breaking theme)haven’t changed water in about three weeks.  Not recommended, but I don’t have a great way to fill it.  I normally use a hose run through the dog door, but the water is just a little too 🥶 chilly with winter going on.  Last water change I lost a few tetras from the shock, so I’m watching the water perimeters.  

I have ecocomplete under a layer of gravel an 20 lbs of crushed coral.  The tank is only 8 months old but seems like it is running smooth.816A1A1A-F8FE-4ECA-B315-A94F40903A02.jpeg.8001f6f1b402133ac0fdf59fd24241da.jpeg










These pictures were at feeding time, please excuse all the food floating in the pictures 

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I don't mean to be "stick-in-the-mud" guy, but if you're going to grow out juveniles and you're hoping for good shape/sized discus, I would personally suggest growing them out in a barebottom tank and changing lots of water.  Doubly so if you're going to feed beefheart or similarly messy concoctions.  

Otherwise, if you're looking for more pleasing views, consider buying larger discus as parameters are less important.  Of course there's all sorts of variables, if you're lucky and you've got softer, acidic water you can get away with a lot more.  Discus are certainly beautiful and challenging in their own ways.  I'd look into where to buy them from... there's a lot of unscrupulous sellers out there.  My experience is that local discus are like 2-3x as expensive as higher quality shipped discus (when buying juvys).  Learn a little bit about what you're looking for (do the eyes look huge compared to the body?  if so it's probably stunted, which might mean it is going to have additional issues down the road).

Once their grown out (in my opinion) that's the time you should start doing some different stuff with your tank.  I'm kind of at a point with mine now that I'd be more comfortable with some sand or something.  But I don't mind the tank being ugly at the moment because the discus are in good shape and still growing well.  I'm happy enough with it at this point.  Most of them are near 5.5" some might be a bit bigger than that.  I got them at 2.5" fish just short of a year ago.


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On 1/30/2023 at 10:23 PM, jwcarlson said:

Of course there's all sorts of variables, if you're lucky and you've got softer, acidic water you can get away with a lot more.

This is a key. Our water is very, very soft. I do not need to run an R.O. system. If the source water you work with is hard, you'll have certain difficulties. Different fish deal variably with alternative sorts of osmotic stress. Discus can thrive if the minerals are low. This is not to say harder water makes keeping them impossible. But it can become more challenging.

Edited by Fish Folk
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Yes, water matters greatly! 


I am keeping them in massively hard water, pH 8.2.  But if I had a bunch of substrate and changed water infrequently there's little doubt in my mind that they would have a lot of issues and look poor. 

There's a reason discus evolved to feed their babies on their slime coat and it's not because their natural environment is teeming with biological activity.  I wipe bottom and sides down weekly, clean filters in tank water about every 10-14 days. 

To be clear, I do not think it much matters what water you grow discus out in so long as it is clean. For me that means lots of water change while growing to meet my goals. And likely more water change even as they are older.  It's not just nitrates that's an issue. 

Edited by jwcarlson
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I would agree with @jwcarlsonhere on the keeping them bare bottom to grow them out, and do frequent water changes while feeding good high quality foods a few times a day. Then, once they are to the 3.5-4" size, I would move them to the planted tank. And, once they reach that size, I am with @Fish Folkon breaking the internet LOL. 

I keep my discus in a planted tank as well, I have some plant aqua soil in media bags capped with Carib Sea peace river gravel, which is a smaller grain gravel or a large grain sand. I have 6 discus, in the 4.5" range in the tank which is a 75 gallon, I have a smaller canister filter and two of the co-op large sponge filters running, and the temp sits in 84-86* range. There are a couple of adult wild Rio Nanay angels in the tank with them, along with German blue rams and black rams, and a few cardinal tetras., and some sterbai cory.  I be sure that all the discus get a fair share of food when I feed, the angels can be hogs when I feed. I feed a lot of frozen foods, bloodworms, brine shrimp, beef heart, as well as some pellets, vibra bites, live blackworms when I can get some, this tank only gets fed once a day, sometimes twice, but if I do feed a second time, it is only pellets and other dry foods.

I do approximately a 30% water change once every week to ten days, clean the sponge filters once a month or so, and the canister filter i haven't opened in at least six months.  My water is  hard and has a lot of minerals in it, I have a well so the pH varies a little 7.6-8.0 TDS is usually between 300-400, I have grown discus out in this water, but my grow out tanks are bare bottom, sponge filters and get a 50% water change twice a week, and fed a few times a day. 



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In addition to the bare bottom, some professional discus growers keep the fry sectioned off in a large tank. That makes them use less energy to find the food while still giving them a large volume of water. It's a little weird to see ten or more young discus sectioned off to one small part of a very large tank, but it works. More food gets eaten with less energy consumed resulting in faster growth while waste still gets diluted in a larger volume of water.

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On 2/1/2023 at 9:16 AM, Marksm33 said:

Thanks for all of the feedback.  I think I will start my fish in my 60 gallon cube tank as juvies as a growout tank and then transfer them to my 125g planted tank.  Feedback was great!

I did 10x2.5" in a 75 with sponge filters (very little current) and changed 90% of the water daily.  They turned out swell.  You should be fine growing them out in a 60 as long as you keep the water quality in good shape.  In the grow out you can pot some plants and grow them that way so you don't have to completely sacrifice aesthetics.  I just had no luck with that, though I just found two floating anubias last night, so I'm thinking the fish are sabotaging my attempts to a certain extent!  

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