01
What actually counts as "nano"
Most of the hobby considers anything under 20–30 liters nano, but the number matters less than understanding how small volumes behave. Temperature shifts faster, pH swings more easily, and one overfed afternoon can stress a 10L tank in a way a 100L tank would barely notice.
That's not a reason to avoid small tanks — it's a reason to be intentional with them. The ones I've kept running the longest are all heavily planted, lightly stocked, and on a consistent routine rather than a reactive one.
02
Cycling before you stock anything
Cycling is the process of growing the bacteria that convert fish waste — ammonia into nitrite, then nitrite into nitrate. In a nano tank, that bacteria colony has very little margin. A tank that looks perfectly clear can crash within a day or two of stocking if it hasn't cycled properly. Always test for ammonia and nitrite. Clear water doesn't mean safe water.
Live plants help speed things up since they absorb ammonia directly. Even so, give a new tank several weeks before adding anything sensitive — especially crystal shrimp. And add livestock gradually so the bacteria colony has time to keep up with the bioload.
03
Shrimp keeping 101
Shrimp are more sensitive to parameter swings than most nano fish, and especially sensitive to copper — which is lethal even in trace amounts. It shows up in some fertilizers and tap water sources. Always confirm that anything you add to a shrimp tank is copper-free.
Neocaridina — cherry shrimp, blue dreams, and similar — are the best starting point. They tolerate a wider range of water conditions and breed reliably without much intervention. Caridina like crystal reds are a different story — they need soft, acidic, and especially stable water, and do best in a tank that's been running steadily for months.
📥 Download Free Neocaridina Care Guide (PDF)
04
Choosing nano fish without overstocking
The most common mistake isn't picking the wrong species — it's overstocking the right one. Chili rasboras, CPDs, and micro rasboras all need groups of six to eight or more to feel secure and show natural color. That bioload adds up quickly in a small tank.
Pick one schooling species, stock a proper group, and resist the urge to add more. A 10L tank with a full school of chili rasboras will almost always look better and run more stable than the same tank split between four different species.
05
Planting for small spaces
Light and CO2 need to be balanced. High light without CO2 tends to fuel algae rather than plant growth — the plants simply can't use the extra light fast enough. For low-tech tanks, keep lighting moderate and stick with undemanding species like anubias, java moss, and bucephalandra. They do well tied to hardscape and left alone.
If you want a true carpet — dwarf hairgrass, monte carlo, and similar — plan for medium-high light and pressurized CO2 from the start. Without it, these plants tend to melt rather than just grow slowly.
06
Equipment essentials
Filter flow is one of the most commonly mismatched pieces of nano equipment. A filter rated for 40L can turn a 5L shrimp tank into a washing machine. Look for adjustable flow, or add a pre-filter sponge to protect shrimp and fry from the intake.
The same applies to heaters. A standard 50–100W heater will overshoot badly in a few liters of water. Nano-rated heaters in the 15–25W range hold temperature much more precisely. For lighting, a small clip-on or bar light is usually plenty for a single nano tank.