Maintaining a healthy and thriving aquarium is about more than just adding fish and decorations. The items you introduce into the tank can significantly impact the water quality, the health of your aquatic life, and the overall ecosystem balance. Whether you’re a beginner or an experienced aquarist, it’s essential to know which items can be harmful or even deadly. Here are 10 things you should never put in your aquarium.
1. Unwashed Gravel or Sand
Adding substrate directly into your tank without rinsing it thoroughly can cloud the water and introduce harmful debris. Dust, dirt, and residue from packaging can quickly turn your clear tank into a murky mess. Worse, unwashed gravel may contain toxins or contaminants that can harm your fish. Always rinse substrate multiple times until the water runs clear before placing it in your aquarium.
2. Soap or Detergents
When cleaning your tank or decorations, it may seem logical to use soap or household cleaning products. However, even small traces of soap residue can be lethal to fish and invertebrates. Soap contains chemicals that break down oils, which can destroy the protective slime coat on fish and disrupt the water’s pH balance. Always clean aquarium items with plain water or use aquarium-safe cleaning products.
3. Metal Objects
Never place metal decorations or objects in your aquarium. Metals, including copper, zinc, and iron, can corrode over time, releasing harmful substances into the water. Copper, in particular, is toxic to invertebrates like shrimp and snails. If you want to add decorative items, stick to aquarium-safe materials like resin, plastic, or ceramic.
4. Untreated Tap Water
While convenient, adding untreated tap water directly to your tank can be dangerous. Tap water often contains chlorine or chloramine, which are harmful to fish. It can also carry heavy metals. Always use a water conditioner to remove these chemicals before adding tap water to your aquarium. Alternatively, consider using a reverse osmosis (RO) filter system for a purer water source.
5. Sharp or Jagged Decorations
Rough or sharp-edged decorations may look appealing, but they can harm your fish. Species with delicate fins, such as bettas, angelfish, or guppies, can easily tear their fins on jagged surfaces. Always choose smooth, rounded decorations, and inspect new items for sharp edges before adding them to the tank.
6. Shells and Coral (in Freshwater Tanks)
While shells and coral may seem like beautiful natural decorations, they can wreak havoc on the water chemistry in freshwater tanks. These items leach calcium and other minerals into the water, increasing the hardness and raising the pH. This can be dangerous for freshwater fish that require stable, soft water conditions. Shells and coral should be reserved for saltwater aquariums.
7. Unquarantined New Fish or Plants
Adding new fish or plants directly to your tank without quarantine can introduce diseases, parasites, or unwanted hitchhikers. Even fish from reputable stores can carry illnesses. It’s best to quarantine new fish and plants for at least two weeks in a separate tank before introducing them to your main aquarium. This helps prevent outbreaks that can harm your entire tank population.
8. Live Food from Unknown Sources
While live food can be a nutritious treat for your fish, sourcing it from untrusted suppliers or wild environments is risky. Live food can carry parasites or harmful bacteria. If you want to offer live food, buy it from reputable aquarium stores or breed your own. Frozen or freeze-dried alternatives are safer and still offer nutritional value.
9. Over-the-Counter Medications
Medications designed for human use should never be added to an aquarium. Some aquarists mistakenly use antibiotics, antifungals, or disinfectants intended for humans to treat sick fish. These medications can be toxic to fish, invertebrates, and beneficial bacteria. Only use treatments specifically formulated for aquarium use and follow dosage instructions carefully.
10. Plastic Toys or Decorations
It might be tempting to add fun plastic toys or random trinkets to your tank for decoration, but these can be hazardous. Most plastic items not intended for aquariums can leach chemicals into the water, harming your fish. Additionally, some plastics break down over time, releasing microplastics into the water. Always choose aquarium-safe decorations made specifically for underwater environments. Please Note: This content was created with the assistance of AI and thoroughly edited by a human before publishing.
