Choosing Your Tank: Bigger is Better.. Right? (Part 2)

For most of my life and up until maybe three years ago if someone new to the hobby asked me if bigger was always better I would have answered without hesitation yes. For the most part this piece of wisdom does indeed hold up, even today. This accepted wisdom holds up to scrutiny for reasons that are actually really important if even still just surface in depth. The ground that it sits on however is very shaky indeed. Lets examine the questions is bigger always better.

What bigger actually is, is more open in stocking options, more expensive, and much more forgiving. Generally speaking with a larger tank size, you have a bigger room by which your fish can move. This means that you can keep bigger fish that require bigger territories. This is a clear example where bigger is better. In smaller tanks, there is less length thus less room for the fish to move. Less room means more stress, more stress leads to reduced success in fishkeeping. Bigger is also more forgiving because of the volume of water that can be used to dilute mistakes and degrading conditions. Bigger can conceal when filters aren’t quite cycled and it can give the hobbyist some wiggle room when the filter itself isn’t up to the challenge of the bioload its being asked to cover for. Thus the new hobbyist having been advised to go as big as they could afford to go is a bit more successful not because of any demonstrated skill but because the volume of water used bought that aquarist more time for filters to mature, for plants to start their life processes and for poisons to dilute to less harmful levels while the filter started up. All of these things are positive and they actually do happen in larger bodies of water. Here is what they don’t tell you. First bigger tanks are more expensive to maintain. Lets look at a filter for instance. In the case of a 30 gallon long tank, a Seachem Tidal hang on the back filter would cost the hobbyist $49.02 as of 7/28/26 on Amazon with Prime. A 75 gallon tank would require a larger filter so when we look for the appropriate Seachem Tidal hang on the back filter we see a cost of $74.25 for a filter that would adequately filter the volume of water. The raw price to purchase is not the only way in which that tank is costing the hobbyist more. Each month the Seachem Tidal 35 uses 6 w of electricity. Whereas the Seachem Tidal 75 uses 8 watts of electricity. So each month the larger filter does filter a larger volume of water and costs the hobbyist more in energy costs. This isn’t the only thing that will cost more. It will cost more to light the aquarium as well. A 30 gallon long is typically 36 inches long. This means that the hobbyist if they were using Fluval lights would need a size 23 to 35 inch FluVal 4.0 Plant light which costs $174.00 as of 7/28/26 at Petsmart. This light uses 32 watts of electricity. A 75 gallon tank has a length of 48 inches. This length would require a Fluval 48 - 60 inch FluVal 4.0 Plant light which costs $240.00 at PetSmart as of 7/28/26. This light uses 59 watts of electricity. Bigger here doesn’t really mean better as clearly the cost to the hobbyist of purchasing equipment and maintaining that equipment is higher with the larger tank.

Bigger is also not always the right choice. In ,my fishroom, my most valuable spaces are my smaller tanks. While my larger tanks are species only and can look quite empty, my smaller tanks is where my baby fish grow out, where fish some fish must be spawned, where my live food is cultured, where sick fish are treated, where new additions go through quarantine and where problem fish are culled. Bigger tanks would not be better for any of these purposes. Let me explain in each now why smaller is better. Baby fish can be dumb. They can swim all around and miss the fact that you just put food into their tanks. If the babies are clustered into a smaller space, there is less chance that they miss when food is deposited into their tank. Because they are concentrated they tend to detect when food is around them and they all begin to feed almost immediately. This means they all eat. In a larger tank this is not always the case. Some fish are so far away that by the time they realize food is available and get to the food your already gone feeding other tanks. These babies if your not careful can easily starve, thus the bigger nature of the tank led to them missing a meal either partially or completely. Smaller tanks are where my live foods are cultured. As dumb as babies can be, ramshorn snails can be even dumber. In this instance when you put in food pellets (usually algae wafers) they can be crawling over any number of surfaces and in a large tank they can completely miss that food is available while others happily scarf the entire quantity down. Snails usually die in really large tanks before they come of age and of the size useful for my puffers, thus I grow them out in smaller volumes, each has a much smaller length to travel and I lose far less to a lack of food. The smaller length also makes locating and catching them much easier on me the hobbyist. Smaller 10 gallon tanks are my hospital tanks. These are also my quarantine tanks. These types of tanks are much better to use for these purposes for one simple reason. They are less expensive to operate. Medicine in the fish keeping hobby is like medicine for humans. It can be extremely expensive. When you have less of a volume, you use less medicine to medicate the fish. Over medical periods that can be over two weeks depending on severity of what is being encountered this means I can treat the fish for a fraction of the cost in my 10 gallon as it would take in say my 75 gallon or even 40 breeders. Bigger here just makes it cost more, it doesn’t help me at all. The increased volume doesn’t really even help me with water quality as the filters on all tanks are mature and I tend to gravitate toward medicines that are relatively filter safe and rarely if ever have the need to use medicine that can stress out or knock out the bacteria in the filtration. Sometimes as an active breeder a fish is born that has obvious birth defects, sometimes it has marking s that make it immediately undesirable and should not be allowed to pass on its traits to a new generation. Rather then passing the problem on, responsible breeders remove the problem. I choose to remove these problem organisms with a leaf fish. The leaf fish is plodding, slow, and tried to imitate a floating leaf. It does this creeping up on fish and when they are within striking range it eats them before they know what hit them. If I put the leaf fish in saw a 30 long, it would take forever for the fish to eat the culls. Some of the culls if they are wily enough that they may even succeed in growing big enough to evade being eaten by becoming too big to consume. Thus putting these fish in a restricted volume increases the leaf fish’s efficiency and it is able to do its job faster than it would otherwise be able to do. Bigger here would just cause problems because fish that should not be passed on would grow big enough to where they would live simply because they outgrew the predator.

The last reason that bigger is not always better is that bigger requires more maintenance. 30% in a ten gallon tank is 3 gallons. Contrasting 30% in a 75 gallon tank is almost 23 gallon. A single bucket replaces the water you take out in a ten gallon. You need five, five gallon buckets to change out 30% of the volume in a 75 gallon tank. That is five times the work removing water and five times the work replacing the water in each tank. Bigger tends to mean a lot more time invested in maintenance.

So I hope you realize by now that while bigger has advantages. This not absolute. Bigger is not always better, there are in fact very real drawbacks to larger tanks. So the next question is how do you decide what is right for you. In general you choose a tank based on how big the fish you wish to keep get. If you don’t know how big the fish will get, now is the time to do your homework. If you don’t know where to start use the resources around you. Ask people in a fish club most if not all will either help you or point you to the person who can help you, listen to vloggers “species profiles” on their youtube channels for instance, and you can also consult the many resources available in both print and the internet. For fun lets consider what I did when I chose to take in the species Geophagus sp. Alto Sinu, or the Gold Dust Earth Eater into my fishroom. A quick consultation of the literature showed me that I was dealing with a fish that grew 5 - 7 inches depending on if it was a male or a female. If I housed this fish in a 30 gallon long tank, it would have 13 inches, just under twice the size of an adult to turn itself around. This would have in my opinion been too small to safely allow it to freely swim the length and feel secure. Thus a 75 was the only option because it allowed for this animal to easily turn itself around even when traveling at greater speeds. This is how you decide, you research the size of the animal, you research its needs (for instance angels grow in height) I would need to account for this in a tank. If I was to house angelfish I wouldn’t choose my 30 gallon long, because with the substrate it would be just uncomfortably shallow for the animal that grows large in height. I would choose the 38 gallon because of the extra height for angelfish. Once you have identified what is important for the animal in your care you purchase a tank that will comfortably allow it to move and address its biological need to swim as an adult. If you do this before getting your fish, you will not run into the mistake many aquarists run into purchasing a fish intending to buy a bigger tank for it later, and then later life happens and that bigger tank never comes. The animal then languishes in a volume too small for it which adds to its stress and lowers its quality of life. Where will you put the tank? This is a question that must be addressed as you need to have the room it requires, you need to level that area if it isn’t level, Does it have electrical access (you will need it), and you need to make certain that the floor is built well enough to handle the filled weight of the tank. After considering where it will be placed, the final consideration depends entirely upon the humans in the household most especially you. You will maintain this tank. This means you have to factor in the cost of its maintenance in time and money. These are the considerations that you need to address before bringing any animals to their new home.