Volcanic Shrimp

Dear Moon Valley:

It’s great to hear that your seahorses and volcano shrimp are doing so well. It sounds like you are doing a fine job of maintaining your red feeder shrimp or volcano shrimp (Halocaridina rubra) thus far, so I would keep on with the maintenance schedule and feeding regimen you have been following.

As long as the pH is where you want it, then the level of calcium isn’t a crucial factor for maintaining these hardy little shrimp. But it’s never a bad idea to add a little calcium to live foods that will eventually be fed to your seahorses in order to help avoid "soft plate syndrome," which is characterized by decalcification of the seahorse’s bony exoskeleton and can result from a diet that is deficient in calcium, as discussed below:

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Soft Plate Disease:

Seahorses and pipefish that receive a diet deficient in calcium are prone to "soft plate" syndrome, which is a progressive disease characterized by decalcification of the bony plates that fuse together to form the exoskeleton (Greco, 2004). In the olden days, this was often a problem with seahorses that were fed a diet consisting solely of Artemia (Greco, 2004). We now know that brine shrimp (Artemia spp.) contains inadequate levels of calcium and an imbalanced ratio of calcium to phosphorus, making it unsuitable as a staple diet even when enriched (Greco, 2004).

Seahorses afflicted with soft plate syndrome exhibit shortened lifespans, decalcification of their exoskeleton, and poor survival rates amongst their fry (Greco, 2004). Pregnant males face the greatest risk of soft plate. Seahorse fry are known to incorporate calcium provided by their father into their skeletons during their embryonic development, so when a gravid male is deficient in calcium, his rapidly growing offspring typically suffer high mortalities due to a condition akin to rickets in human children.

Fortunately, this debilitating condition is easily prevented by providing seahorses with adequate levels of bioavailable calcium either in their diet or in the aquarium water itself (minerals can be obtained by fish directly from the water; Greco, 2004). I have never heard of a case of soft plate in a seahorse kept in a reef tank that received Kalkwasser (calcium hydroxide) via an automatic doser or regular supplementation of bioavailable calcium. Nor have I even seen this condition in seahorses that received a stable diet of enriched frozen Mysis relicta.<close quote>

So feel free to add a calcium supplement to your volcano shrimp setup, Moon Valley, if you like to raise the level of calcium a bit. Just don’t overdo it or add the supplement too often — adjust the calcium level very gradually and monitor the calcium levels regularly if you’ll be supplementing.

Here are some water quality parameters to keep in mind:

Basic Water Quality Parameters.

Ammonia (NH3/NH4+): Optimum level = 0 at all times

Ammonia is highly toxic to both fish and invertebrates in even small amounts (> 0.01 mg/L or ppm). Causes of ammonia toxicity include: immature biofilter (new tank syndrome), impairment of the biological filtration due to antibiotics and other medications, overfeeding, overstocking and dead specimens that go undetected (Webber, 2004).

Nitrite (N02): Optimum level = 0 at all times

Nitrite is slightly less poisonous to fishes than ammonia, but deadly to many invertebrates at very small concentrations (0.01 mg/L or ppm). Even trace amounts of nitrate such as this can wreak havoc in a reef tank and cause serious distress to fish. High levels of nitrite result from the same causes as ammonia.

Nitrate (N03): Optimum level = below 10 ppm in fish-only tanks; 0 ppm in reef tanks.

Nitrate is the end product of the process of nitrification, formed during the Nitrogen Cycle by the oxidation of nitrite by aerobic bacteria. Nitrate is relatively nontoxic to fishes, but elevated levels (> 20 ppm) are stressful to seahorses over the long term and promote the growth of nuisance algae. Reef invertebrates can be much more sensitive to nitrate, and concentrations as low as 0.06 mg/L can cause problems for symbiotic stony corals. The nitrate level is therefore a good indicator of water quality. For best results, consider using live rock and/or a live sand bed (preferably situated in your sump) in conjunction with a good protein skimmer to help filter your seahorse setup. The skimmer will remove excess organic compounds before they enter the nitrogen cycle, and live rock and a deep sand bed will provide significant denitrification ability, all of which will help keep your nitrates down. Don’t overstock, don’t overfed, remove leftovers promptly (a good cleanup crew is useful here), grow and harvest macroalgae, practice good aquarium maintenance and maintain a sensible schedule for water changes.

pH: Optimum level = 8.1 – 8.4 (typically fluctuates between 7.9 at night and 8.4 during the day)

The pH is a measurement of the alkalinity or acidity of aquarium water. A pH of 7 is considered to be "neutral," neither acid or alkaline, while pH levels above 7 are considered to be alkaline or "base," and pH levels below 7 are considered to be acidic. Marine aquaria need to maintain alkaline conditions at all times, and low pH (< 7.6) is especially detrimental to seahorses because it is conducive to Gas Bubble Disease. Normal daily fluctuations in pH are to be expected in the aquarium, and are generally gradual enough not to be stressful (Webber, 2004). Maintaining a sump or refugium with a reverse photoperiod to the main tank can eliminate these natural pH cycles. Regular partial water changes are the key to maintaining stable pH. Buffers can also help but the hobbyist should beware that excessive use of pH buffers may increase KH values to dangerously high levels.

Dissolved Oxygen (02): Optimum level = 6 – 7 ppm

High levels of dissolved oxygen are vital to the well being of both fish and invertebrates. The key to maintaining high O2 levels in the aquarium is good circulation combined with surface agitation (Webber, 2004). Wet/dry trickle filters and protein skimmers facilitate efficient gas exchange and oxygenation. It is important for the hobbyist to monitor the dissolved oxygen levels in the aquarium because a drop in O2 levels is often an early indicator of impending trouble — a precursor of problems ahead. A drop in O2 levels will tip off the alert aquarist and allow corrective measures to be taken, nipping the problem in the bud before it adversely affects his seahorses.

Alkalinity: Optimum level = 2.4 milliequivalents per litre (meq/L), which is the alkalinity of natural seawater, is best for fish tanks; > 3.0 meq/L is recommend for reef tanks.

The alkalinity is basically a measure of the capability of your aquarium water to resist changes in pH from the addition of acid (Trevor-Jones, Nov. 2002). Acid is continually entering the aquarium, primarily as the result of respiration (CO2) and metabolic wastes produced by the aquarium inhabitants (Trevor-Jones, Nov. 2002). The addition of these acids tends to lower the pH of the aquarium water. The higher the alkalinity of your aquarium water, the more resistant it is to such downward pH shifts (Trevor-Jones, Nov. 2002). The amount of buffers (primarily carbonate and bicarbonate) in saltwater determines the alkalinity, so the alkalinity in effect is the buffering capacity (Trevor-Jones, Nov. 2002). When the buffering capacity of the water is depleted, the pH becomes unstable. Alkalinity test kits can now warn of low buffering levels in time to prevent potential pH problems (Trevor-Jones, Nov. 2002).

Carbonate Hardness (KH): Optimum level = 7dKH (the hardness of natural seawater)

Carbonate hardness is another measurement of alkalinity. It is usually expressed in the German unit dKH (degrees of carbonate hardness) and is often considered to be the total alkalinity. (Dividing dKH by 2.8 will give you the alkalinity in meq/L.) KH actually a measurement of various carbonates and bicarbonates of calcium and magnesium within the aquarium water (Webber, 2004). Maintaining a stable KH is very desirable since it maintains the buffering capacity (i.e., alkalinity) of the system and prevents subsequent drops in pH. Aside from stabilizing the pH, reef keepers need to maintain KH and high alkalinity in order to assure that the calcifying organisms in the tank flourish. Corals and other calcifying organisms actively use bicarbonate, which is the main component of alkalinity, so the alkalinity of a tank with a lot of calcification can drop quite rapidly.

Calcium (Ca): Optimum level = 350 – 400 ppm (up to 500 ppm in well-stocked reef tanks)

Calcium is a very important element in the water in any marine aquarium and is a vital element in reef tanks. Along with carbonates and bicarbonates, it is required by calcifying organisms such as stony corals, snails and other mollusks, coralline, Halimeda and other calcareous algae, and certain sponges (Trevor-Jones, Apr. 2003). Calcium reserves must therefore be replenished on a regular basis. Regular water changes may achieve this, but reef keepers may require the addition of biologically available calcium to maintain adequate levels (Trevor-Jones, Apr. 2003). Seahorse keepers should be aware that brooding males provide calcium to the developing fry in their pouches, which the embryos probably incorporate into their skeletons. Deficiencies in calcium could thus adversely affect your seahorses’ reproductive success and the health of the fry. In fact, seahorses that receive a diet deficient in calcium often suffer from decalcification of their exoskeleton, a debilitating condition commonly known as “soft plate” disease (Greco, 2004).

Phosphates (PO4): Optimum level = as low as possible in fish-only systems

High phosphate levels are detrimental to marine aquaria. In fish-only tanks, they promote excessive growth of nuisance algae, and in reef tanks they also directly inhibit calcification by corals and coralline algae (Holmes-Farley, 2002). Phosphates arrive in the aquarium in fish foods, through tap water, as an ingredient in low-quality carbon and marine salt mixes, and primarily through the waste products of the inhabitants (Webber, 2004). Phosphates can be removed by using commercial phosphate-binding agents, but growing and harvesting macroalgae and protein skimming are the best ways to reduce phosphate levels

Redox Potential or Oxidation Reduction Potential (ORP): Optimum level = 350 millivolts

The redox potential relates to the degree of water purity in the aquarium, and can be thought of as a measurement of the water’s ability to cleanse itself via oxidation. It is measured in millivolts of conductivity, a unit that provides information about the reduction and oxidation characteristics of the water. (“Redox” is merely a contraction of reduction-oxidation.) Oxidation-Reduction Potentials (ORP) are closely related to the stability of the marine aquarium and can therefore be used as a barometer of water quality. Highly efficient filtration, good aquarium maintenance and management, and the use of ozone in conjunction with a protein skimmer will help to boost redox values.

Seahorse keepers with fish-only systems need not be overly concerned about many of the parameters mentioned above, but I’ve summarized them anyway for the sake of thoroughness and the benefit of reefers who keep seahorses.

Best of luck with your seahorses and your volcano shrimp, Moon Valley!

Happy Trails!
Pete Giwojna