Do you need rocks in your cichlid tank?
Cichlids tend to be quite aggressive and territorial fish. Many aquarium stores minimize this aggression and maximize water clarity by keeping large groups of juveniles in bare tanks. This prevents the establishment of territories and diffusing the aggression across a wide range of potential targets.
While some hobbyists may choose this ‘bare’ route with certain species for breeding purposes, it makes for a dull tank that will actually contain a lot of stressed-out fish.
Rocks for aesthetic appeal
Most hobbyists will prefer their tanks to be showpieces, and both the substrate and decorations are an integral part of this. While some will opt for bubbling scuba divers and treasure chests, keeping fish in a more “natural” habitat will frequently lead to happier fish and a more balanced and attractive tank.
Particularly if you’re keeping African cichlids or Central American ones, this means you need some rocks. Sometimes you’ll need a lot of rocks, depending on what you’re keeping and the size of your tank. While a 20 gallon tank with some Tanganyikan shell-dwellers may not need very much, a 180 gallon tank of Mbuna from Lake Malawi may need literally hundreds of pounds of rocks.
Rocks for cichlid territory building
Many cichlids, particularly those from the rift lakes in Africa, dwell in and around rocks in their natural habitat.
The rocks provide caves, allow for the establishment of territories, and are often breeding sites for many fish. Additionally, in the home aquarium, the lights provide hiding places for fish that are being picked on and break up line of sight to reduce aggression.
Where Can I Buy or Get Rocks?
Rocks are everywhere. The problem is that not all rocks are equal, particularly in home aquariums.
Some rocks can dramatically change the water chemistry, or release potential contaminants such as heavy metals into the tank which can be quite detrimental to your fish. Additionally, if you just add rocks directly, the odds are high that you’ll also be adding a host of bacteria and other potential pathogens that can devastate an expensive tank.
Many aquarium stores sell rocks. Often these will be special varieties which are quite attractive like rainbow banded sandstones.
The advantage here is that in general the rocks available are aquarium safe and need minimal preparation before being added to your tank. The big disadvantage is the cost; these rocks are normally sold on a per pound basis, which adds up fast.
If you have a small tank and don’t want to take any risks, buying aquarium rocks is the way to go. We recommend beginners take this option too.
Collecting rocks to use in a cichlid tank
Rocks can be collected from many different sources. They can come from the seashore, from river beds, or from your garden. Many different rock types will work in your tank; fortunately you don’t need to be a geologist to figure these out.
Granite and slate are easy to recognize and both are inert. Sandstone is not recommended since it is often crumbly and can literally dissolve in your tank. Limestone will increase the water hardness, which can be problematic if you’re keeping species that require soft, acidic water but can be a great option for African cichlids who naturally live in very hard, alkaline water (aka: liquid rock).
(A test you can do to find out whether a rock is limestone, add a few drops of vinegar. Calcium carbonate in the rock will react and fizz.)
Avoid rocks that have metallic-looking streaks in them, as those are often veins of metallic ore, which could be very detrimental to your fish if anything is soluble in the water over time.
Also avoid rocks that have lichen or other persistent plant growth on them (don’t worry about algae; we’ll take care of this before adding them to the tank.)
Jagged rocks should probably be avoided as well, since they have the potential to inflict injuries on your fish.
Some aquarists prefer smooth river rocks, some like flat stones stacked, and others prefer oddly shaped rocks to ensure a more secure stack with less possibility of rock falls in the tank. It’s an aesthetic consideration that is entirely up to the individual.
Treating the rocks you have found before adding to your tank
Before placing your newly found rocks in an aquarium it’s important to reduce the possibility of introducing harmful pathogens to the tank.
If the rocks are relatively clean (no algae), then this can normally done by making stone soup and boiling them immersed in water for 20 minutes or so.
If there is algae present, or you’re particularly paranoid (not a bad thing in this hobby), then placing them in a bucket in a solution of 3:1 water to bleach (get the cheap stuff that does not contain detergents) for an hour will kill most plants and bacteria. These should then be rinsed thoroughly a few times, and it couldn’t hurt to put them through the stone soup method afterwards.
We do not recommend beginners to take this on. Buying your cichlid rocks, although more expensive upfront will e worth the investment versus the disastrous consequences of getting the above wrong.
Things to consider before placement of rocks in your cichlid aquarium
You’ll want to stack your rocks up to create caves and hiding places for the fish.
It’s important when doing so that you do not lean rocks against the glass walls of the tank, as minor shifts could readily lead to catastrophic cracks.
Larger rocks should be placed first as the base, and these should be well buried in the substrate. Remember that some cichlids are active diggers, and if you have any of these, this must be accounted for or you may have avalanches down the road.
Each stone should be carefully placed, and jiggled and rocked to ensure that it’s secure before placing the next one. In this manner, you can build some very cool areas and focal points.
For those with particularly large species or who are worried about collapse, you can also buy sealants that are aquarium safe and can be used underwater to glue your rocks together. Note that this means you can’t change up the décor freely when you are bored with it or if you need to scramble territories, but it is possible.
While rocks are great in tanks, another trend that has become popular over the last few years involves rock alternatives, particularly as a tank background.
The big advantages here are the reduced weight and a much lower chance of rock-falls damaging the walls of your tank. Additionally, with a little planning you can hide the requisite heating units and aquarium filter intake and output behind this background (being sure to leave enough space for the water to circulate properly).
The disadvantages are that the project is either quite expensive if you go with a commercial option, or a labor intensive DIY project, but the results can be stunning. Check out the Youtube video for an example of how to do this.
DIY Tank Background
In the tank shown below, we did a variation on this using acrylic paint covered with a marine-safe epoxy which had sand sprinkled across the final coating which gave a pretty natural look.
Rocks are an integral part of many cichlid tanks. They are simple to incorporate, inexpensive if you collect your own, and allow for an aquarium hobbyist to exercise their creativity and play with design elements that can take any fish tank to the next level as a showpiece while providing a natural habitat for the fish.