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Bacteria and Algae Growth in Tropical Fish Tanks

Fish Care

By Jeffrey Williams

Algae Growth in Tropical Fish Tank

Image Source: DepositPhotos

Bacteria and algae growth in tropical fish tanks are the two main types of pests threatening the quality of your fish tank's water. While some merely look unpleasant, others can become threatening to the flora and fauna within the aquarium. In this article, we will discuss them separately and propose some of the most effective prevention and eradication tactics.

Tropical Fish Tank Bacteria: Friend or Enemy?

As humans, we are raised to believe that bacteria are scary and life-threatening organisms that should be feared. However, these creatures are common to the emulated ecosystem inside tropical fish tanks, and they aren't dangerous for the most part. In fact, some varieties thrive due to the established nitrogen cycle within the tank.

The Nitrogen Cycle and Its Bacteria

Otto Algae Growth Eater, Otocinclus affinis
Otto, Algae Growth Eater

The two main types of bacteria that reside in fish tanks are autotrophic bacteria and heterotrophic bacteria. Autotrophic bacteria are self-reliant, as they are able to synthesize food for themselves with the help of inorganic substances such as chemicals or light. The beneficial organisms in the tank's filter belong to this category.

Beneficial bacteria are responsible with the processing of fish waste into nitrates, a less toxic compound, and subsequently into harmless nitrite. However, other types of fish tank dwellers belong to the autotrophic category of microorganisms. One example is the blue-green cyanobacteria, which has the appearance of rust-colored algae growth when in bloom.

While a buildup of cyanobacteria is certainly inconvenient, it rarely produces damages to aquatic life. What is more, the slimy mat they create is easily removed from the fish tank through a simple siphoning process. Heterotrophic bacteria are the true concern in this situation, as they break down nutrients inside the tank into ammonia.

How to Prevent Bacterial Blossoms

The most common bacterial infestation in tropical fish tanks is known as a bacterial bloom, or a bacterial blossom. It occurs when a rapid increase in the number of live colonies within the aquarium water takes place due to excess nitrates and phosphates. This generally happens due to overfeeding or improper tank hygiene regarding the prompt removal of dead fish and plants.

When tropical fish tanks are affected by bacterial blossom, the invaders become visible to the naked eye due to their rapid multiplication. Thus, the water appears as cloudy or murky. Sometimes it can even get hard to see the fish inside anymore. Unfortunately, heterotrophic bacteria are the main culprits for this problem.

Here's how to prevent bacterial blossoms. Fortunately, it's not a complicated procedure. As mentioned above, overfeeding and improper cleaning are the two main causes behind. The answer is thus obvious. Ensure that you always offer your fish just the right amount of food, and always remove dead fish immediately. This won't allow the heterotrophs to thrive and clog up the tank.

Pathogens, Diseases, and Other Dangers

Unfortunately, the aforementioned types of bacteria aren't the only ones that can lurk deep within your fish tank. According to the Center for Disease Control and Prevention, pathogens such as Salmonella, Streptococcus iniae, Mycobacterium marinum, and Aeromonas commonly infect our finned buddies. The worse news is that they are transmittable to humans as well.

To prevent this for the sake of your health, as well as the wellbeing of your family members and of the fish themselves, always practice caution when handling aquatic creatures. Wash your hands thoroughly before and after, and always purchase new tankmates from certified sellers only. Set up the aquarium just right, paying attention to the little guys in the process.

Types of Algae Growth

Algae Growth in Tropical Fish Tanks
Image Source: DepositPhotos

While bacteria are single-celled prokaryotic microorganisms, algae growth is an entirely different creature altogether. They can be either unicellular or pluricellular, and they are eukaryotic in nature. There are four main types of algae that infest fish tanks, and they are categorized depending on their color. Here they are explained, in no particular order:

  • Green algae. If the water in your tropical fish tank starts looking like pea soup, it means that you have a case of green algae overgrowth on your hands. The main causes behind it are dissolved waste and disproportionate exposure to light. In small quantities, green algae is an excellent food source for the inhabitants of the tank.
  • Blue-green algae. A consequence of poor water quality, blue-green algae are different from the corresponding bacteria. They take over every surface in the tank, and might even stick to dormant fish. If the little guys start looking like moldy rocks, you'll know why.
  • Red algae. When the water in your tropical fish tank lacks the necessary amount of carbon dioxide, red algae start to develop. They are nasty little things, as they hang around in threads everywhere and interrupt the smooth functioning of the tank's miniature ecosystem. They are also a pain to get rid of, and you will most likely have to clean everything up and start from scratch.
  • Brown algae. While excessive light causes green algae, the opposite will lead to brown mounds of the same type of organism.

Managing Bacteria and Algae Growth

When your algae problem gets out of hand, it is time to perform some routine operations that will ensure you are managing bacteria and algae growth. Take these steps to ensure your tropical fish tank stays as clean as possible. Start with 10% water changes until the problem clears up. If this doesn't happen, try using a scraper or control products. You can most likely find these accessories at any local pet shop.

To combat the problem from within, add live plants and algae-eating fish. While plants will feed off of the same nutrients the algae need to survive, and thus put an end to their reign, fish will simply gnaw on them anytime they want a tasty, chlorophyll-rich snack. This will keep the invasion in check and ensure that the water in the aquarium remains of the highest quality.

The Bottom Line

Bacteria and algae growth are two different types of organisms that affect your tropical fish tank in divergent ways. The best way to protect the living beings inside the aquarium from their action is by practicing prevention through proper hygiene. When things get out of hand, treatments are available, but it's best to not let the situation escalate in the first place.