Will the corydoras catfish be in this tank? There is a HUGE debate in the fish-keeping world about substrates that are smooth enough for corydoras catfish and their sensitive barbels. They can be prone to barbel erosion caused by bacteria. Some people say that a clean substrate is more important than the size or texture of the pieces. On the other hand, a few corydoras fans feel so strongly about substrate that they think a planted tank may be incompatible with keeping corydoras. To get around this problem some people use a thin layer of sand and only plants which attach to driftwood or rocks, or those which are not picky about substrate, like in this tank
You can Google 'Corydoras substrate' and you will find many forum discussions about this topic.
Corydoras catfish live over sand substrate in the wild. Some sands are even too coarse for Corydoras catfish though so even a sand selection will have to be made carefully. Some plants can grow quite well in sand substrate. However, sand can be difficult to keep clean since fish waste will always settle on top of the sand. Sucking up some of the waste with an oral syringe between water changes will help.
FYI, CaribSea (white) Moonlight Sand
is very fine, which is supposedly desirable for cories which sift through the sand. Plants should be able to grow in it as well. Plants with large root systems need at least 2-3 inches of substrate, but having more than 2 inches of sand increases the risk of developing anaerobic air pockets. Weekly stirring of the sand, and/or mixing it with a little bit of pea gravel may help prevent this.
Now back to your original question. I think Flourite is a great specialty plant substrate. It comes in a mixed red/black
(used in this Eclipse 6 gallon betta tank), an all black, and perhaps an all red coloration. (If you decide to use Flourite, look up recommendations for how to rinse it. If you don't rinse it it can be very dusty in the tank.) Some corydoras owners say their cories do fine on Flourite. Flourite can be expensive depending on where you live, but you will just need 1 bag with a 5 gallon tank. Using a gravel siphon during weekly water changes to suck up fish waste will help keep the substrate clean for the cories. The Flourite pieces look jagged but when you rub it between your hands you should feel no sharp edges.
Another popular specialty plant substrate is Eco-Complete. I have seen some tiny pieces in this substrate that seem kind of sharp so I don't think I can recommend it for cories. Some people have their cories on Eco-Complete but I have heard a few of them say that they would choose a different substrate if they could choose over again.
Ok, here is something else to consider. Keep in mind that the moss balls and anubias plants will not care which substrate you use. The anubias can be attached to small pieces of driftwood with nylon fishing line or cotton thread.
I'm sorry I couldn't give you a clear-cut answer but I hope I at least gave you a few options to consider. :)
Originally Posted by vaygirl
What should I use? I'm getting ready to set up a 5 gallon and I did river rocks in my 16 but that was before I decided to plant. I'll be moving some marimo balls, a little four leaf clover, some wisteria and a full grown anubias nana into the new tank, so what do ya'll suggest?