Decomposition Rate of Brine Shrimp Eggs

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There has been some concern that extra hatched and un-hatched brine shrimp eggs that get into feedings of live brine shrimp will cause problems in the tank they are in.

These brine shrimp egg shells tend to accumulate along the top rim of tanks, and are readily drawn into sponge filters where they can accumulate in very large numbers. The theory is that they will be broken down by bacteria which in turn, will cause a couple problems in the tank. One assumption is that the increased ammonia and nitrites the bacteria produce, will not be readily handled by the bio-filter and will cause problems generally associated with high levels of ammonia and nitrites. The other problem would be the result of the large increase in these heterotrophic bacteria, which would attack the fish. This would possibly cause internal and/or finnage problems.

(2/13/01) After observing no problems from huge numbers of excess brine shrimp egg shells in the artemia shell experiment involving angelfish eating large numbers of these shells, I concluded that the cyst covering, decomposed very slowly. Today, I took the filter out of that test tank (test still in progress), and squeezed it out for the first time since that experiment started. The number of brine shrimp egg shells trapped in this filter was incredible. It appeared as if almost every shell that had been put in this tank during this test, ended up in the filter, without being decomposed. The fish at this point, still show no signs of a high bacteria load and the tank has zero ammonia and nitrite levels.

Test: I've decided to test the decomposition rate of several items. I will have each sample in it's own container. The items will be live newly hatched brine shrimp, fresh flake food, dried decapsulated brine shrimp egg cysts, previously hatched brine shrimp egg shells, and regular un-hatched brine shrimp egg cysts. They will be kept in a room that is approximately 85°. The pH is 8.2 and the water is moderately hard. These conditions will generally promote fast growth of heterotrophic bacteria. Observations will be made once each day and recorded.

One half cup of tank water was placed in 5 small plastic containers. As water evaporated, tank water was added to each container (twice a week). These were placed on a shelf, 24" from an overhead fluorescent light. A quarter teaspoon of each type of brine shrimp eggs was place in its own separate container. The live brine shrimp was the amount approximate to what would hatch from a quarter teaspoon of cysts. A single flake, 2" x 2" was put in the other container. I thought this size flake would approximate a quarter teaspoon of flake, if crushed.

7 Days Later

  • Hatched brine shrimp shows substantial deterioration. You can still make out that it is brine shrimp, under a scope.
  • Flake food has deteriorated approximately 25%.
  • Decapsulated dried brine shrimp eggs shows a wide range of deterioration. Approximately 25% of the cysts appear the same as when the test started. The rest show various rates of deterioration, with all having at least 25% of the yolk still left.
  • un-hatched brine shrimp eggs appear the same as when the test started. 5)Brine shrimp egg shells seem to be unaffected at this point.

14 Days Later

  • Hatched brine shrimp has deteriorated about 95+%. Under a scope, it appears that all that is left is a clear ecto-skeleton.
  • Flake food has deteriorated approximately 75%.
  • Appearance of Decapsulated dried brine shrimp eggs is about the same. There is some fungus-like growth on the outside of the shell, but the inside of each shell, still contains about the same amount of material.
  • un-hatched brine shrimp cysts appear the same as when the test started, with the exception of some fungus-like growth on the outside of some. It actually looks like some of the shells have split open and the brine shrimp has partially emerged. This may be causing some of the fungus growth.
  • Hatched shells have been unaffected at this point.

30 Days Later

  • Hatched brine shrimp has deteriorated completely.
  • Flake food has deteriorated approximately 95%. I was somewhat surprised that some flake was still remaining. I wonder if these are the portions that contain a higher amount of preservative.
  • Decapsulated dried brine shrimp eggs are not showing significant deterioration. It is becoming difficult to see this sample because of fungus and algae growth. It appears if most of the inside of each shell, still contains some material, but not much.
  • un-hatched brine shrimp eggs appear the same as when the test started, with the exception of some fungus-like growth and algae growth in the container. It looks like some of the shells that had contained the partially emerged brine shrimp, are now empty.
  • Hatched brine shrimp shells still seem to be unaffected at this point. There is algae growth in this container also. I believe the bright light overhead is causing this.

55 Days Later:

  • Hatched brine shrimp was deteriorated two weeks ago. Test was discontinued.
  • Flake food has deteriorated completely.
  • Decapsulated dried brine shrimp eggs appear to have completely deteriorated, but the clear shells are hard to see with all the algae in the sample.
  • un-hatched brine shrimp cyst looks like all the outer shells remain, but most if not all have had the cyst spit open and the brine shrimp has decomposed.
  • Hatched brine shrimp shells still seem to be unaffected at this point. There is still quite a bit of algae and some bits of fungus in the sample, but all the shells appear intact and just like the first day they were put in the test.

Conclusions: Live brine shrimp decomposed rapidly as expected. Most of the flake food decomposed almost as quickly, but a small amount of flake took a longer time to decompose than I expected. The clear inner shell that remains on decapsulated brine shrimp eggs, does not seem to decompose very quickly, but the material inside does seem to be readily affected. I'm guessing that the clear shell splits open, but the split is difficult to see on this clear layer. un-hatched brine shrimp eggs also exhibited a different reaction than I expected. The outer shell was completely unaffected, but after at least a few weeks, it appears that most of the shells split open and the decomposition of the internal material then takes place. Hatched brine shrimp egg shells showed no sign of decomposition. It is my belief that if no deterioration has taken place after 55 days, it is not a concern in the management of our aquariums.

© 2006 Angels Plus