Why keep marine aquaria?
The extraordinarily vividly colored and frequently quite distinct fish is without a doubt the major attraction of saltwater aquaria. Even cichlids cannot compete with the vibrant colors of coral reef fish, and no freshwater species can compete with the stunning finnage of a lionfish or the quaintness of a cube fish.
There are also numerous other species that may be found in salt water, such as corals and anemones, starfish, sea apples, urchins, crabs, snails, and others. Many of them are amazing in and of themselves, but seeing them interact with other species, such as a clownfish and its anemone, is even more enjoyable. In salt water, you may create a micro-ecosystem or just appreciate the fish for their vibrant colors.
Is it more difficult?
So, what makes folks hesitant? Most people believe that maintaining a marine aquarium is more difficult than maintaining a freshwater one. The minor regular water changes advised for marine tanks should also be undertaken on freshwater aquaria. A freshwater system, on the other hand, maybe more tolerant of slackness. In a freshwater tank, if water changes are not conducted, algae may develop excessively and fish may get unwell, although a thorough clean-out can remedy most issues. However, if a saltwater tank is ignored, excessive nitrate levels may cause a catastrophic die-off, resulting in a significant stock loss.
A marine tank requires a larger initial expenditure than a standard freshwater system of the same size (although, not as much as some would have you think). There is also some extra work needed, such as combining sea salt and monitoring water quality. These tasks are simple and take just a few minutes, but they must be completed on a regular basis if your marine tank is to thrive. Setting up a marine tank takes a bit more patience as well; fish must be introduced one to two at a time, and establishing a reef system might take months.
About saltwater & marine habitats
Almost all marine fish sold in supermarkets originate from tropical coral reef regions like Australia’s Great Barrier Reef. However, there is a rising interest in preserving temperate marine species, such as that found off the coastlines of Southern Australia. Understanding the ecosystems from which marine fish originate is essential for better understanding their demands in aquaria.
Two factors are true of all maritime ecosystems, regardless of whether they are temperate or tropical. The first is that, even when fish dwell in high numbers (like on reefs), the sheer amount of water around them ensures that waste product concentration is quite low. Second, in terms of temperature, salinity, pH, and other water quality characteristics, the oceans are relatively stable.
What does this indicate for everyone interested in keeping marine species in aquariums? Because these fish are from such a steady habitat, they do not tolerate extremes in water quality, rapid changes or variations in water quality, or waste product accumulation. Many people feel that because of this, they are more difficult to maintain than freshwater fish, however, this is not always the case. It is not difficult to maintain the conditions that marine fish need provided the aquarium is correctly set up.
Requirements of marines
To effectively keep marines, you will need to spend more on equipment than you would in freshwater. Very effective biological filtration is required to maintain proper water quality for marine fish, and it is strongly suggested to evaluate water quality parameters (e.g., pH, ammonia, nitrite, nitrate) to ensure they remain below acceptable levels.
The chemical composition of salt water, both in the seas and in aquaria, aids with pH stabilization. This is because carbonates and other small chemicals are present, which neutralize acids without producing pH shifts. However, if carbonates become depleted (as they may in aquaria), pH may decrease fast, hence carbonate hardness testing is also advised. Alkalinity is another term for carbonate hardness. Although they are not technically the same (carbonate hardness is the carbonate content, while alkalinity is the total content of compounds that neutralize acid), most carbonate hardness tests are actually testing alkalinity, which includes carbonates as well as other trace minerals that are present in minute concentrations.
You’ll also need a hydrometer to monitor the salt concentration, and you may want to invest in a high-quality heater that can keep the temperature more precisely than a cheap one. A cooling system may be required for temperate marine life.
The good news is that with proper filtration, maintaining your marine system is simple. Water changes should be done on a frequent basis to keep waste products down, although minor water changes are preferable to minimize big swings in water quality.
Water quality for marines
What are the water quality needs of marine fish and organisms?
Specific gravity (a measure of salt concentration) should be between 1.015 and 1.025, whether tropical or temperate. Most marine creatures have an optimal specific gravity between 1.020 and 1.022. Most fish and even invertebrates can tolerate slightly greater or lower specific gravity as long as it remains steady. The pH level should be between 8.0 and 8.2, with 8.2 being optimum. A high carbonate hardness of 100 to 125 mg/L (6 to 7°KH) or above is preferred for pH stability.
Temperature stability is also significant. The optimal temperature for tropical marine fish is 25°C. Temperate animals will be affected by the ambient temperature of their surroundings. For example, the seas off the coast of South Australia remain at approximately 18°C for most of the year, making this the optimal temperature to preserve fish from this location.
The concentration of waste products such as ammonia, nitrite, and nitrate in coral reefs is so low that they are nearly undetected. While ammonia and nitrite may (and should) be maintained at undetectable levels in the aquarium, keeping nitrate at zero is frequently impossible when fish are present. (For additional information on the nitrogen cycle and the significance of biological filtration, see our Filtration FAQ.)
With the exception of a few vulnerable species, most marine fish have a fair tolerance for nitrate and can withstand 50ppm or more. Many invertebrates, especially corals and anemones, may begin to suffer at nitrate concentrations as low as 10ppm. Protein skimming and frequent water changes help to keep nitrate levels low and having a lot of living rock or a deep sand bed may help with de-nitrification (the natural breakdown of nitrate). However, the more fish in the tank, the more nitrate is likely to be present and the more difficult it is to regulate. If you want to retain particularly delicate corals and invertebrates, you must keep them in an aquarium with few fish. Although temperate fish are less susceptible to nitrate, maintaining levels below 50ppm is still advised.
About invertebrates
One difference between freshwater and marine aquarium maintenance is the presence of species other than fish, known as invertebrates. What exactly are invertebrates? Invertebrates include all creatures without a backbone, including insects, snails, crustaceans (such as crabs and shrimps), and a variety of others. They are not just confined to maritime environments. However, there are numerous invertebrates in the water that are extremely different from the species we are acquainted with on land. Many of them, especially corals, seem to be plants rather than animals since they are linked to a solid surface and reproduce by budding! They are, however, creatures capable of capturing food delivered to them by ocean currents. Other varieties can move; some move very little, while others move quite a bit. The water is home to a variety of unique organisms, some well-known, such as starfish, but others less so, such as the closely related sea urchins and sea cucumbers (also called sea apples).
One of the pleasures of owning marine aquariums is the variety of creatures.
About marine plants
Another distinction between marine tanks is the variety of “plants” available. There are, in reality, very few genuine plants that grow in saltwater, and none that are suited for aquaria. Rather, the majority of “seaweeds” are macroalgae. A few varieties, mostly Caulerpas, are available for marine aquaria, but not nearly as many as are available for freshwater aquaria.
Corals (in the case of a reef tank) or limestone, sandstone, or slate rocks may be used to decorate a marine aquarium. Of course, any aquarium decoration, including silk and plastic plants, shipwrecks, and imitation corals, may be employed.
Can I collect my own animals?
You may be able to harvest at least some marine species, but two conditions must be met.
First, check your local regulations regulating the acquisition of aquatic life. In South Australia, for example, it is forbidden to gather organisms from the intertidal zone (the area between high and low tide, including rock pools and down to a submerged depth of 2m) or from any locations designated as marine reserves (eg Aldinga, Noarlunga reef). A few species are protected (for example, Leafy seadragons), although it is permitted to collect non-protected species from subtidal regions less than 2m deep (ie from areas that remain submerged by 2m even at the lowest low tide). Size and bag limitations apply, and they are the same as for recreational anglers. Regulations in other locations differ greatly, so verify your local laws!
Second, consider if your setup is suited for the sorts of fish you want to capture. Temperate water species (especially invertebrates) often cannot handle temperatures beyond 20°C, thus you will almost certainly require a cooling device to effectively retain them. Fish are typically more tolerant, but to be sure, examine the requirements of your local species. The Marine Life Society of South Australia is a good place to start for South Australians interested in learning more about our indigenous species and their care in aquaria.
Can I collect my own saltwater?
It is typically not suggested to gather salt water for use in home aquariums. There are two major issues. The first step is to secure a clean supply. Even distant from big cities, freshwater runoff necessitates the collection of salt water a kilometer or so offshore. Second, the waters are home to billions of tiny creatures (known as plankton). When water is taken from the ocean, the plankton die, and the water gets contaminated rapidly.
Temperate or tropical? Marine fish or reef aquarium?
Before you get started with marine aquarium keeping, you need to pick what kind of livestock you want, since this will define what equipment you will need.
The first option is to choose between temperate and tropical species. Tropical species are the most popular since they are the most plentiful and colorful. Warming the water is also less expensive than installing a cooling system. Temperate species, on the other hand, are not without attraction. Many may be picked by hand, which is pleasant, and many are as intriguing as their tropical cousins.
If you choose tropical marines, you must pick whether to set up a fish-only system or a reef tank. Keeping a reef tank, which is mostly corals and invertebrates with just a few fish, is not difficult, but it requires more equipment than a fish-only system. Maintaining a fish-only marine aquarium is much simpler. However, as previously stated, keeping corals and other delicate invertebrates in a tank with a high fish load is quite challenging. As a result, you must select if you want a reef with a concentration on corals or a tank with fish as the primary show. Although a fish-only marine aquarium is often used, this does not exclude the inclusion of invertebrates. Starfish, urchins, and sea apples, as well as certain shrimp and crabs, have a high nitrate tolerance. If you choose the reef tank route, the equipment you’ll need will vary based on the varieties of coral you want to preserve.
