What is the most dangerous thing a new aquarist can do?

The aquarium is all set up, the fish have been added and now it is time to sit back and enjoy the flashes of color that you see as the fish move within the living picture you have created.  One of the most enjoyable times is watching the fish as they go into a frenzy right after the tank is fed.

Feeding is the time when most people feel the closet to their fish, it is when you are able to fulfil the most basic need the fish have, to have the nutrition that allows them to be active and as colorful as possible.  The problem is that often this can be the most dangerous activity a novice aquarist perform!

Fish do not live in the same environment that humans do, and the most natural action is to anthropomorphize the fish into being just like you.  Mistakenly equating needing food to survive and in the same quantities that land animals do.  The problem here is that fish are nothing like mammals, they have very different nutritional requirements and most of that is due to the fact that fish are poikilothermic.  That is a very fancy way to say the fish are cold blooded, their body temperature very closely matches the outside temperature and tracks the changes as the temperature rise and falls over time.

The fact they are poikilothermic is possibly the most important fact a new aquarist needs to completely understand, so that the ramifications are clear.  You and I use about 85% of the calories we consume to keep out body temperature regulated at a precise level to allow all the various chemical and biological processes we have developed to operate efficiently and effectively.  Our bodies tell us when we are hungry and we most often consume nutrition three times a day.  Most of these calories are burned as heat to keep up at our proper body temperature.

Fish do not need all those calories, they stay at the temperature of the water around them. If t rises and falls dramatically, then the fish will become stressed and often sicken.  That is the reason that the heater in an aquarium is one of the most important pieces of equipment.  It needs to keep the temperature at a tropical level, and steady over time.  We have often warned about allowing sunlight into the tank, it can play havoc with the temperature over the course of a day.  Keeping away from hot and cold air ducts are also important in maintaining the proper levels over time.

The most natural belief is that the fish should be fed the same way people eat, three times a day, but that is very dangerous to the fish, for two reasons.  First, they don't need extra calories to heat their body, and secondly they never evolved the homeostatic control to tell them when they are full.  

When you sit down to a meal, you eat util you feel full. there are sensors in your body that tell you when you have eaten enough.  Sugar levels rise as well as other indicators that tend to stop you from overeating.  Fish do not have these mechanisms.  They are in a hostile environment where food may not come regularly so they have been programmed to eat as much as they can whenever the getting is good. 

I have seen fish act as if they are starved after being fed every five minutes for an extended period.  Each feeding sends them into a frenzy and they swallow as much as they can.  Some have even ruptured by eating too much.  They also have never been accused of being careful eaters.  They don't keep food to a centralized place rather most foods are scattered over the top and then if the flakes or pellets are not eaten they can drop to the bottom where they are most often totally ignored. 

Bottom fish should not be fed at the same time as the swimming fish above. they are programmed to eat food that has deteriorated over time, and rarely touch food that drops from the surface preferring to eat food that has rotted or otherwise been missed by the top fish after the food has time to soften and deteriorate in some way.

So, how does one prevent a disaster from occurring when feeding.  The first is to prevent too much food entering the habitat in the first place.  I recommend feeding no more than twice a day as much as the fish can eat in two minutes with nothing hitting the bottom. If there are wasted flakes or pellet hitting the bottom, then you have overfed.  The bottom fish prefer the partially digested food expelled as feces by the top fish, so trying to feed the bottom fish is a waste of time.  Let the natural processes of the fish digestion provide the sustenance for the bottom dwellers.   

Steve Pond
Tropical Fish Aquarist

Harlequin Rasbora: The Jewel of Southeast Asian Streams

Introduction

The Harlequin Rasbora (Trigonostigma heteromorpha) stands as one of the most beloved and recognizable freshwater aquarium fish in the hobby. This stunning cyprinid, native to the forest streams of Southeast Asia, has captivated aquarists for decades with its distinctive appearance and peaceful demeanor.

Physical Characteristics

Measuring a modest 1.5 to 2 inches when fully grown, the Harlequin Rasbora boasts a diamond-shaped, laterally compressed body adorned with a rosy-orange to copper base coloration. Its most striking feature is the distinctive black triangular patch that begins at the middle of the body and tapers elegantly toward the tail. This "harlequin" marking gives the fish its common name and makes it instantly recognizable. Males typically display slimmer bodies with more vibrant coloration and sharper-edged black wedges, while females appear rounder, especially when carrying eggs, with slightly softer edges to their markings.

Natural Habitat

In their natural habitat across Thailand, Malaysia, Singapore, and Sumatra, these rasboras inhabit slow-moving forest streams, tributaries, and peat swamps characterized by dense vegetation and tannin-stained blackwater. These environments feature very soft, acidic water with pH levels between 5.0 and 6.5, low mineral content, and heavy canopy coverage that creates dim lighting conditions. Understanding these natural conditions is crucial for successfully maintaining these fish in captivity.

Aquarium Requirements

For the home aquarium, Harlequin Rasboras require thoughtful setup to thrive. While a minimum tank size of 10 gallons can house a small school, a 20-gallon or larger aquarium is preferred to provide adequate swimming space for these active fish. Water parameters should ideally mirror their natural habitat, with temperatures between 72-81°F, pH levels of 6.0-7.5 (though 6.0-6.5 is ideal), and soft water with hardness between 2-12 dGH. The tank should be heavily planted with live vegetation, feature a dark substrate to enhance their colors, and include driftwood and leaf litter to create a naturalistic environment. Subdued lighting and gentle water flow complete the ideal setup.

Behavior & Compatibility

As peaceful schooling fish, Harlequin Rasboras must be kept in groups of at least six individuals, though groups of 8-12 are preferable for displaying their natural behaviors and reducing stress. They occupy the middle to upper regions of the water column and spend their time actively swimming in loose schools. Their peaceful temperament makes them excellent community fish, compatible with other small, non-aggressive species such as tetras, Corydoras catfish, small gouramis, and peaceful barbs. However, they should not be housed with large or aggressive fish that might view them as prey or outcompete them for food.

Feeding Requirements

In terms of diet, Harlequin Rasboras are omnivores that feed on small insects, worms, crustaceans, and plant matter in the wild. In the aquarium, they readily accept high-quality micro pellets or flakes as their staple diet, supplemented with live or frozen foods such as brine shrimp, daphnia, and bloodworms. Their small mouths require appropriately sized foods, and they should be fed small amounts 2-3 times daily. A varied diet not only maintains their health but also enhances their coloration.

Breeding Information

Breeding Harlequin Rasboras presents a moderate challenge that requires specific conditions. A separate breeding tank with very soft water (1-3 dGH), acidic pH (5.3-6.0), and temperatures between 76-80°F provides the best chance of success. The breeding tank should include broad-leaved plants like Cryptocoryne or Anubias, as these fish have the unique behavior of laying eggs on the undersides of leaves. During courtship, males display intensified colors and perform elaborate dances to attract females. Spawning typically occurs in the morning hours, with females depositing 30-50 eggs that the male fertilizes. Parents should be removed after spawning to prevent egg predation. The eggs hatch within 24-36 hours, and fry become free-swimming after 3-4 days, requiring microscopic foods like infusoria before graduating to baby brine shrimp.

Health & Lifespan

With proper care, Harlequin Rasboras can live 5-8 years in captivity. They are generally hardy fish but can be susceptible to common ailments such as ich, fin rot, and internal parasites, particularly when stressed or kept in poor water conditions. Their sensitivity to water quality changes makes stable parameters essential, and regular maintenance, including partial water changes and filter cleaning, helps prevent disease. Quarantining new fish before adding them to established tanks further reduces disease risk.

Special Considerations

Several special considerations deserve attention when keeping Harlequin Rasboras. They display their best colors in well-planted tanks with dark substrates, which provide contrast to their vibrant hues. Without adequate cover or when kept in insufficient numbers, they may become shy and reclusive. As accomplished jumpers, a secure tank lid is essential. Their peaceful nature, while making them ideal community fish, also means they're vulnerable to fin-nipping species and should be protected from aggressive tankmates.

Purchasing Tips

When purchasing Harlequin Rasboras, look for active specimens with bright colors and avoid any showing signs of disease such as clamped fins or white spots. Buy from reputable sources and consider implementing a quarantine period before introducing them to your main display tank. Always purchase them in groups to reduce stress and encourage natural schooling behavior.

The Harlequin Rasbora's combination of striking appearance, peaceful nature, and relative hardiness has cemented its position as a staple in the aquarium hobby. When provided with appropriate conditions that mirror their Southeast Asian origins, these living jewels reward their keepers with active displays of schooling behavior and vibrant colors that enhance any community aquarium. Their enduring popularity is a testament to their adaptability and charm, making them an excellent choice for both beginning and experienced aquarists seeking to add a touch of elegance to their aquatic displays.

Creating Your Underwater Eden:

Aquascaping a Small Community Aquarium

Embarking on the journey of setting up an aquarium can be an exciting venture for beginners. One of the most rewarding aspects of this process is aquascaping – the art of arranging aquatic plants, rocks, and driftwood aesthetically in your fish tank. In this article, we'll guide you through the basics of aquascaping a small community aquarium of about 10 - 20 gallons.

Planning Your Aquascape

Before you begin, it's important to have a clear vision of what you want your aquarium to look like. Research different aquascaping styles and find one that resonates with you. Two popular styles you might consider are the "Nature Aquarium," which mimics natural landscapes, and the "Dutch Aquarium," characterized by lush, densely planted setups.

Remember that your aquascape should not only be aesthetically pleasing but also functional for your fish. Ensure there are ample swimming spaces and hiding spots to accommodate your community's needs.

Choosing Substrate

The substrate serves as the canvas for your aquascape and plays a crucial role in plant health. There's a variety of substrates to choose from, including sand, gravel, and specialized plant substrates. For a planted tank, consider a nutrient-rich substrate that supports plant growth. Layer the substrate so it's deeper in the back and shallower in the front, which creates depth and perspective.

Adding Hardscape Elements

Hardscape elements like rocks and driftwood form the backbone of your aquascape. They provide structure and create focal points. When selecting these elements, ensure they are safe for aquarium use. Limestone, for example, can alter water hardness and pH levels, making it unsuitable for certain fish and plants.

Driftwood can leach tannins into your water, slightly tinting it and lowering pH levels. While this isn't harmful and can even replicate some fish's natural habitats, it may not be the look you're going for. You can pre-soak driftwood to minimize tannin leaching.

Note: Always boil or soak hardscape materials and scrub them clean to remove any potential harmful substances before introducing them to your tank.

Planting Your Aquarium

Plants not only enhance your aquarium's aesthetics but also help maintain water quality by absorbing nitrates. Choose a mix of foreground, midground, and background plants to create a sense of depth. Carpeting plants like Dwarf Hairgrass or Java Moss are excellent foreground choices, while taller plants like Amazon Swords or Java Ferns can form a lush backdrop.

Decorations and Ornaments

Decorations can add personality to your aquascape. However, be cautious with the type of decorations you choose. Some materials, like certain metals and paints, can leach harmful substances into the water. It's best to purchase aquarium-safe decorations from reputable pet or aquarium stores.

Maintenance Considerations

Once your aquascape is set up, proper maintenance is key to keeping it healthy and vibrant. Regular water changes, appropriate lighting, and fertilization (if you have live plants) are essential. Prune plants regularly to ensure they don't overgrow and block light to lower-dwelling species.

Conclusion

Aquascaping your small community aquarium is a creative and fulfilling process. By carefully selecting your substrate, hardscape, and plants, you can create a beautiful underwater paradise for your aquatic pets. Remember, the best aquascape is one that caters to your fish's needs and reflects your personal style. Happy aquascaping!

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