Challenges in establishing a nano ecosystem


Nano tanks are a huge area of interest for Sam’s Aquariumz. Many people perceive fish bowls or small glass tanks as somehow, easier than a traditional filter tank. But, this is not necessarily true. If you aren’t experienced then you can end up with a terrible environment for your fish. There are a three main issues with nano tanks that can actually make them more challenging, that someone new to fish keeping may not know about.


  1. Less space for bacteria


Many new to the hobby do not really have a concept of beneficial bacteria. They see cloudy water or algae on the walls as bad and will change all the water and completely scrub the glass; this is not the best plan. In reality, a brand new tank is literally just tap water. Water is not a habitat. Think about a fish’s environment in the wild for a moment and you can begin to comprehend the complexities involved and obviously, the water is not clear.


Bacteria are essential to eat all the dead matter and poop that begins to break down in the aquarium. As all the uneaten food and poop sits on the bottom, it starts to decompose into the chemicals nitrite and ammonia. Without bacteria, these chemicals pollute your water and affect the ph and overall make a bad environment for your fish; it’s literally acids burning their scales. Picture him/ her just sitting in compost water essentially.


BUT there is hope. The bacteria will actually eat up the ammonia and nitrite and convert it to nitrate, which plants love and fish do not mind as much (some are sensitive though). This is what is called the cycle. In general the cycle happens small scale throughout time as ammonia always rises and falls. In general though, a new tank is considered cycled when ammonia and nitrites will have peaked to a deadly level, and then fallen off as it it is converted to nitrate.


In order for this to happen the tank actually needs some waste to build up initially. Many aquarists cycle their tanks by feeding the tank a bunch of fish food, or adding snails to start pooping and get the process going. This waste creates a lovely home for a new bacteria colony to develop. But these bacteria don’t just float around in your water, they are literally on every surface area. Therefore, more surface area = more bacteria= safe cycling in your tank.


This brings us around to the problem with nano tanks, they just don’t have the surface area or in some cases don’t have the sponge filter to collect bacteria. That’s why filters always contain porous materials for ‘biological’ filtration. Those dirty little white ceramic pieces are actually a great home for the bacteria. Without this, there really aren’t much places for them to live in a nano tank. This is why live plants and a proper porous rocks for substrate are essential. Check out our substrate section for some unique options.


In such a small space you inevitably also have less animals that produce less waste and make it hard for that initial cycle to happen and to stay steady over time. This is why I don’t suggest doing only shrimp right off the bat, as they just don’t produce a lot of waste. That’s why I would put a hardy fish in first (feeder gold fish) as well as a healthy snail colony and wait a few weeks at least before adding any shrimp or nano species. When you think it’s been long enough, take your water to a pet store and they will let you know when nitrates are up and the cycle is complete or be a boss and invest in a test kit and just actually learn to do it yourself and monitor regularly.


  1. More fluctuation


With less water in a nano tank it means that even a small scoop of water, percentage wise, is considered a decent water change in a nanotank. It can be tough when you are trying to clean the bottom, but inevitably take out 50% + of the water which normally would.never happen in a big tank. This takes out a tonne of your bacteria and makes your tank vulnerable to cycle again. In a small space your tank is also vulnerable to temperature shifts. An open window or even the furnace coming on is going to greatly affect your residents even if you have a heater in your tank.


  1. Less space


Nano tanks are well, nano. They are a small space for a fish or shrimp who probably has a tonne of space in the wild. There’s a lot of misconception about what species can be kept in nano tanks. A lot of this surrounds bettas. Research shows that bettas do live in small ponds as a natural environment… but ponds are not bowls, plain and simple and this shouldn’t be the argument as to why they can be kept in bowls. On the flip side we must also be realistic, this is not a wild animal. Genetically, bettas are so far removed from their naturally selected ancestors that the factors that affected their evolution just are not relevant any more. In reality, bettas have become commercially successful because of their ability to survive in poor water conditions with fluctuating ammonia and nitrites, plain and simple. Personally, I think that space more plays a role in the fish’s happiness and stress level. A betta in a tank with lots of space will swim around more and probably be more colorful than his brother who floats in his bowl alone, and he may also not live as  long as a result. But, to an owner who has never conducted this experiment they probably say their betta is very happy and I’m not going to disagree with this. The point of this is that just because a fish can live nano doesn’t mean it should as it may not be that happy.


Small space creates an additional issue of the fish not having the space to burn off steam. The vast majority of nano species deaths I’ve had have been from fish jumping out. When you keep little schooling fish like danios and barbs in a tank with no lid they will inevitably chase eachother around. Check out my ‘building a nano tank’ blog post  for suggestions of species I’ve found that can handle fluctuation, don’t become stressed in small spaces and are less likely to jump out.


In conclusion, if this stuff confuses you or scares you off at all, then a bigger tank or at least something with a filter is probably the right decision for you!