Agg's Discus Guide
I am an experienced aquarist who has recently begun keeping Discus fish. I found when doing my research that there is a LOT of information available, but much of it is conflicting. Also, a lot of the accepted knowledge about keeping Discus seems to be persisting from decades ago when Discus were mostly wild caught and a lot more fragile than those available now, most of which are bred in captivity. So, the purpose of this page is to record the knowledge I have collected before I forget it all, and to detail how my real-world experiences match or conflict with that information. As mentioned earlier I am very new to Discus keeping (but have been fishkeeping for nearly 15 years) so my experiences may not be correct for you. But I hope you find this guide useful. Good luck and enjoy your fish!
Discus are unusual in that they are very slow feeders. For most tropical fish many people recommend only offering as much food as can be eaten in two minutes, or five minutes, etc. This will not work with Discus as they prefer to graze and pick food from the bottom of the tank, often for more than an hour after feeding. You don't really get the thrashing feeding frenzy at the surface that you see with rainbowfish, angels and most other tropical fish. You should really feed them at least twice a day, although like any fish one or two days with less food or even no food is not going to harm them, and simulates the natural environment where there are sometimes food shortages. If you don't feed them for a day, they will simply find things to peck at in the tank.
If you look at the "face" of a Discus, they have a very small mouth for their size, and a large brow leading up to the dorsal fin. Because of this they have difficulty feeding from the surface of a tank. Compare for example with a rainbowfish which is excellent at picking food from the surface such as insects which fall into a stream. The rainbowfish has a large mouth positioned well out in front and a sleek torpedo-like body, so has no issues hitting a surface object at speed. Discus often seem baffled by food at the surface, blowing water at it to try and break the surface tension to make it drop. Some of my discus will peck at a pellet sitting on the surface, and very rarely even try for a piece of tropical flake, but in most cases they wait until the food starts to sink. Even then it can be too fast-moving for them and they simply follow it down to the tank floor, then peck at it there. It's also a good idea to turn off your tank filters when feeding, because firstly it trains your fish to come to the front/surface when the filters are turned off, and secondly it means they don't get food being blasted past them too fast to catch.
Discus require a high-protein diet. In the wild they pick worms and crustaceans from the substrate. The staple diet of captive Discus seems to be frozen blood worms, and that's certainly true of mine. I give them one or two blocks of frozen worms with every feed. However I also offer them pellet food, as well as flake, frozen brine shrimp, frozen beef heart mix, etc. Any quality tropical fish food should be fine and it's good to vary the diet of any fish, but Discus definitely prefer and require frozen once-live food. BTW, brine shrimp don't really contain much protein or actual nutrition, but they provide roughage which is good for the digestion.
Live food is generally a bad idea for fish tanks of any kind. If you have a specialised fish like Piranha which will only eat live moving things, then fair enough, if you can handle the cruelty side of it. But be aware living food brings with it the potential for parasites and disease. Even if you trust your source of live food, do you trust their source? I have fed my fish live red worms from my own worm farms, the commercial bin kind which you feed food scraps to, and they have been well recieved. But even though I control everything the worms eat, I'm not really comfortable with introducing live creatures, plus whatever is stuck to them or living inside them, to my carefully-managed aquarium environment. Of course, poor quality frozen food could have the same issues but it's far less likely due to having been frozen for so long.
One thing you find when looking for Discus feeding info is mention of beef heart. This is obviously a high protein food but I'd never really come across it before. Anyway, the net is full of recipes and tips for making your own mixture etc, but it is also available in a frozen block form so I just buy that. There's some suggestion that beef heart is good for them but not in excess, so I give them one block every two days - as opposed to bloodworms which they have every day.
Food I've tried with my Discus
- TetraMin Tropical Flake
- This has been my standard food for as long as I've been keeping fish, of all kinds. Sadly almost all the Discus ignore it, although I have seen the smaller and less fussy Discus blow water at it on the surface to make it drop, and on a couple of occasions eat a flake. But it doesn't really form part of their diet at all. I put it in the tank for the Cardinal Tetras.
- Hikari Frozen Bloodworms
- Accepted enthusiastically by all fish
- No issues
- Fish Fuel Factory Frozen Beef Heart
- Accepted enthusiastically by all fish
- No issues
- Hikari Frozen Brine Shrimp
- Accepted enthusiastically by all fish
- No issues
- Sera Discus Granules
- Accepted by all fish who eat pellets. I have one large Blue Diamond who will only eat frozen food and he does not go for these pellets, or any others.
- They sink almost immediately and sink a little too fast for all but my most agile Discus. They are pecked from the substrate easily enough, though. Two fast-moving smaller Discus can peck them out of suspension as they fall, so I'm hoping the others will get the hang of it.
- Hikari Discus Bio-Gold pellets
- Expensive ($25 for 80g)
- "Slow sinking" according to the packet but realistically they don't sink at all unless disturbed from the surface. So they sit on the surface indefinitely until I turn the filters back on, then they are blown all around the tank and mostly eaten by my cleanup crew instead of the Discus.
- I won't buy these again, and will probably end up feeding most of this packet to my rainbowfish tank, not the discus tank.
- New Life Spectrum Discus Pellets
- Not tried yet, but they are widely recommended online, so will try them soon.
I put the tankmates section below the feeding section because one of the main issues with keeping Discus in a community tank is their poor ability to compete for food. Sharks or rainbowfish or any other fast-moving aggressive feeder is going to beat Discus to the food every time, as well as frighten and buffet them around. As mentioned earlier Discus prefer to pick food from the tank floor, and I know for example in my rainbowfish tank virtually no food makes it to the floor, never mind sits there waiting for a Discus to eat it. I've seen rainbows hit a block of frozen brine shrimp from underneath, hard enough to fire the block out of the tank and across the room, and launch the fish out of the tank onto the glass lids. They also play "bloodworm soccer", where one rainbow grabs the semi-thawed block of bloodworms and races around the tank while the others try to grab it off him. Discus will not cope in that kind of environment - you will never see them because they will be hiding from the fast-moving fish and they will not get enough food.
However, if you have a tank that doesn't have a bare glass bottom, you probably want to have tankmates who will clean up any leftover food so it doesn't go off. The classic companion of Discus is Cardinal Tetras. I have a school of about 50 in my 6x2x2 planted discus tank, and they look fantastic as they move around the driftwood and plants in a large school. They don't compete directly with the Discus for food and will shy away if a Discus comes after food near them, but after feeding time when I turn the filters back on, any leftover flake, pellets or frozen food are taken from suspension by the tetras. To keep the substrate clean I have four bristlenose catfish and for a further general cleanup crew I added about 100 ghost/glass shrimp. They are breeding but also being eaten occasionally by the tetras, so I have no idea how many shrimp are in the tank now, but there are still plenty visible. The bristlenoses and glass shrimp also help keep algae in check.
When I was first looking into keeping Discus I was very nearly frightened away by the horror stories of maintenance required. People talk about doing insane water changes, like 50% every day, or even 100% changes every day, needing UV-sterilised water and Reverse Osmosis machines and all that. This is a classic example of information that has come down from decades ago when all Discus were wild caught. The Discus you find in shops nowadays are the result of decades of captive breeding, so they are much more suited to captivity, in terms of tolerance to water conditions, resistance to illness and temperament.
Personally I have not found them any more difficult than any other tropical fish. My regime is a 25% water change every two weeks, and I occasionally gravel-vac the substrate when the mood takes me. To refill I use tap water which has had conditioner added and then left to age for 24h in a large wheely bin outside with the lid on. I don't pre-heat the water before adding back to the tank. Due to the volumes involved (nearly 200 litres for a 25% change) I don't use buckets, but a hose and pump setup I will detail in a future forum thread.
Now, I may find all my Discus dead one morning, and revise my stance on maintenance, but for now I say if you are scared off by the info you are reading on the net, don't be. Having said that, like any tropical fish tank, you should do the maintenance required. If you want fish you can ignore for months at a time, put some goldfish in a pond outside. If you don't want to spend an hour or two every couple of weeks interacting with and observing your fish and maintaining your aquarium, why did you buy it?