Is My Aquarium Overstocked ?(18+ Signs You Need To Know)

There are many people who like beautiful fishes that lead them to overstock their aquarium with many more fishes, but have you thought about whether it works, that is, Can all fish thrive peacefully in the overcrowded or overstocked environment? Of course not. Let’s know why in detail.

Is My Aquarium Overstocked? Yes, Your tank is overstocked, If it contains many fishes that showing bad water or poor water quality, fish gasping, harassing one another, algae blooms, sick fish, inactive and stressed fishes etc. even though you have installed advanced filter the fishes feel less space leading them to stress.

Can you Overstock a Fish Tank? No, You should not do it because the overpopulated fishes in a Overstock tank feel stress due to less space available for them to swim, less food available them to eat in the fish crowds,especially weak and small fish can’t get foods from the dominant fishes, fishes undergo stress, diseases will be spread fast in the overstocked fish tank, etc

How Do I know if my Fish Tank is Overcrowded?

There are many ways to know your fish tank is overcrowded, overstocked or overpopulated. These ways or signs can be such as 

  • Fishes have less space to swim in your tank.
  • Fish gasp and live at the water surface for atmospheric oxygen.
  • The tank water becomes dusky or dirty, especially when your filtration system stops.
  • Fishes become stressed, diseased, aggressive due to the fish crowd.
  • Fish excreta deposits on the bottom of the tank.
  • Some fish become inactive, hide in a place for a long time and finally die.
  • The fishes might fight, chase, in order to get its food while competing for food.
  • Changes in pH level of water often due to the more fish.
  • Formation of algal blooms on the substrate and on the water surface due to the increased amounts of ammonium, nitrates, fish excreta, rotting foods, etc.

18 Signs That Your Aquarium Is Overstocked

  • Tank water becomes dirty: When a tank becomes overcrowded its water becomes dusky or dirty due the waste produced by the overcrowded or overstocked aquatic animals. The rotting food also causes the water to turn dirty.
  • Tank water undergoes lack of oxygen: When a tank becomes overcrowded its aquatic animals start to use more oxygen causing rapid depletion of oxygen concentration in the water. The lack of oxygen can occur rapidly especially  if there are no natural aquatic plants, filters and air pumps in the tanks. However, If we could manage to set natural plants in the overstocked aquarium we can naturally elevate the oxygen concentration naturally at some extent. This lack of oxygen causes so many problems to the aquarium livestocks.
  • Bad water appears, especially and immediately when your filtration system stops or fails: The best parameter to know whether the tank is overcrowded or not is by temporarily disabling the water filtrations system, that is, If we stop the filtrations system for a temporary period we could see how much and how fast water is being turning into dirty due to the waste produced by the overcrowded aquatic animals and by the rotting food materials.
  • Inadequate Filtration system or Filtration system fail frequently: Frequently failure of a water filtration system is the sign for the overcrowded or overstocked tank as overcrowded fishes keeps on produces the waste that is accumulated in the water that can’t be filtered by the common filtration system shows the tank is being overstocked by fishes and other aquatic creatures. Therefore, A common filtration system is not enough or can’t withstand filtration of dirty water, that is, an advanced filtration system is necessary but even then it can’t solve the other problem such as less space for swimming, hiding, etc.

“You can add advanced filter but can’t increase the space for fish”

  • Fish live at the water surface ( for atmospheric oxygen): Overcrowded fishes depletes the water oxygen concentration leading to gathering of fishes at the water surfaces where some of them are trying to receive atmospheric oxygen while some other fishes receive the dissolved oxygen available at the water surfaces.
  • Fish live at the bottom surface: The weak, sensitive and shy fishes start to live at the bottom of the tanks due the problems and threats caused by overcrowded fishes. The stronger, faster and dominant fishes usually swim, play and launch their territories in the overcrowded tanks leading the other weak, shy, recessive fishes to live and hide at the bottom of the tanks.
  • Frequently fishes fight or compete for space: In overcrowded tanks all fish can’t get enough space for swimming, playing, hiding, eating, mating, etc as a result they start to show their territorial behaviors even though they usually belong to the non-territorial type of species. These territorial behavior or competition for space will start to happen if the fishes are set in the overstocked tanks.
  • Frequently fishes fight or compete for food: In overcrowded tanks all fish can’t get enough food due the presence too much other fishes or crowded fishes, that is, the dominant, fast swimming, big size fishes are competing for foods as a result the shy, weak, small fishes can’t get food at all as a result they undergo starvation.
  • Frequently pH level of water varies: The pH sensitive fishes can’t be healthy in overstocked tanks because the water of the overstocked tanks changes in its pH level frequently due to overstocked tanks fishes than the normal tanks.
  • Fishes undergo diseases rapidly: When compared to undercrowded or normal crowded fish tanks the fishes and aquatic animals of overcrowded tanks develop diseases rapidly due to their contact with the sick or diseased individuals in overcrowded tanks. As a result, this could cause rapid deaths of aquarium animals belonging to overcrowded tanks than other tanks that are undercrowded.
  • Fishes undergo Stunted or slow growth: The overstocked tanks and its fishes put problems in many ways to each other as a result most of the fishes can’t thrive and grow naturally in less spacious environments, that is, in overstocked tanks where there is food scarcity is also a problem. 
  • Fish show gasping behavior: The fish gasping is an important and survival sign of a fish that shows the overstocked tank, that is, In an overstocked tank fish shows gasping behavior due to less space, lack of oxygen, crowded fishes that often occupy one another spaces. These gasping fishes are under death and live or simply in survival situations, especially in overcrowded tanks it should not be ignored. 
  • Fishes show inactiveness, weakness, hiding etc: When the fishes are living in the overstocked environment where there are many stresses are common they become inactive, weak, etc. which is an indicator for overcrowded tanks.
  • Fishes show aggressive behavior, bullying or harassing : Most fishes become aggressive due to the stress, starvation, territorial violence etc. in overcrowded tanks that can lead to hurting one another. They can bully one another for space, food, etc. especially this behavior can happen more in the overstocked tanks as there are more fishes available.
  • Fishes show fin nipping behavior: If there are any kinds of fishes that have fin nipping behavior such as tetras, danios, etc they are going to come up with this fin nipping behavior causing injuries to one another, especially in overcrowded tanks.
  • Fishes undergo stress: There are many reasons that all makes most of the fishes undergo stress that can be scarcity of food or unavailability of food due to the overcrowded fishes, less space for hiding, swimming, mating, lack of oxygen, etc.
  • Fish excreta or waste deposits on the bottom of the tank: The more fish excreta deposition occurs at the bottom of a tank the more it is overcrowded by aquatic animals.
  • Appearance of Algal Blooms: As soon as there is enough fish waste, ammonium, nitrates, rotting food easily available in overcrowded tanks, The formation or the appearance of Algal bloom takes place at all over the tanks, that is, at the bottom, substratum, on the filtration system, rocks etc that indicates the tank is overcrowded by the fishes and other aquatic animals.

How to Maintain an Overstocked Aquarium?

There are many ways to maintain an overstocked aquarium. Apart from increasing the space for an individual. Those methods are as follows.

  • Make sure every individual gets enough food in the crowd: Use of space dividers, or other methods are necessary to ensure all of them, especially the small, weak, shy fishes get food among the big and strong fish crowds in an overstocked aquarium.
  • Install Natural aquatic plants: If there are enough natural plants available in an overcrowded tank it will increase the oxygen concentration in the water that is required for fishes. Natural plants are appreciable, especially if an artificial air pump fails to supply the oxygen.

Installing the Natural aquatic plants also have other advantages for fishes, that is, they enable the places for hiding and mating in them.

  • Advanced filtration system: Use of an advanced filtration system is one way to ensure the overcrowded tank is having clear water that is necessary for thriving by the fishes, especially those thriving in overcrowded tanks. This makes the aquatic animals to live under less stress.
  • Provide enough hiding places by installing rocks, caves, decorative etc: Fish need personal places for hiding, mating, eating, spawning etc., especially when they are being attacked by the bullies, aggressive fishes require some hiding places until the intruder gets away. 

These all make them live in stress free environments even though they are living in overstocked tanks. However there are still more expensive and time consuming methods that can also be used to maintain an overstocked tank but not going for an overstocked tank is best.