Do fish eggs float or sink?
Egg buoyancy. The major fractions of marine fish eggs are pelagic or mesopelagic implying that they float above the seabed.
The majority of clupeiform fishes have pelagic (free-floating) eggs, which float in the surface or bottom water layers. Egg position is maintained by the presence of a large swollen space between the egg itself and the outer membrane.
Unfertilized goldfish eggs are circular in their shapes and look like tiny bubbles, they are bright white in color. They are the eggs that haven't been fertilized by the male goldfish, hence, they float on top of the water. The unfertilized eggs won't result in fish fry.
Eggs incubating higher in the intertidal spend more time out of water than their counterparts in the low intertidal or submerged in subtidal spots. While these soon-to-be-fish out of water may seem in peril, Frommel says they can survive these conditions for extended periods of time, even up to 24 hours.
Once laid, the eggs often look like tiny balls of jelly. These are often scattered to the water, but in some species they end up in a mound on the nesting area, or stuck to the floor or side of the aquarium.
Simply fill a bowl with cold tap water and place your eggs in it. If they sink to the bottom and lay flat on one side, they are fresh and good to eat. A bad egg will float because of the large air cell that forms at its base. Any floating eggs should be thrown out.
Characters most useful in identification of fish eggs are the following: (1) egg shape-spherical, ellipsoidal, irregular, or oth- erwise; (2) egg size-fish eggs range in size from 0.5 to 26.0 mm; (3) oil globules-presence or-absence.
When the natural eggs are laid, some do not get fertilized during the spawning procedure and become a murky, whitish color. These dead eggs sometimes can save the day when fish become extremely finicky. Finally, carrying patterns that range from single eggs to egg clusters can also be a good idea.
Breeding Strategies
The eggs may be scattered, deposited or buried, depending on the species. Scattered eggs either fall to the substrate, float to the surface or stick to plants, rock or whatever else they come in contact with. The eggs hatch quickly and the fry are on their own to survive.
Egg buoyancy. The major fractions of marine fish eggs are pelagic or mesopelagic implying that they float above the seabed.
Can you squeeze the eggs out of a fish?
Do not try to squeeze or force the eggs from the fish; this will only in- jure the female. Frequent or rough handling of females retards ovula- tion, reduces spawning success and increases fish mortality.
Salmonid (trout, salmon and whitefish) eggs are disinfected using an iodophor solution. Iodine is the active ingredient which kills the bacteria and viruses.
The best kept secret in determining an egg's freshness is to see if it sinks in water. To try the egg water test, simply fill a glass or bowl with cold water and submerge the eggs. If the eggs sink to the bottom and lay flat on their side, they're still fresh.
Female fish lay eggs, with the eggs being fertilized by the males in close attendance. Eggs develop more rapidly (in a few weeks) in warmer temperatures, and more slowly in colder water (up to months). Most freshwater fish spawn in the spring, although salmon, char, and some trout spawn in the fall.
But even under the best conditions, at least 70% of newly hatched fish still die. For example, the Tel Aviv researchers found that at Har Dag, a veteran fish farm in Eilat, typically 250,000 larvae survive from one million hatched eggs.
Incubation. After about 30 days, the fish embryos develop visible eyes, or "eye up". We then safely sort the live versus dead and count these now "eyed up" eggs. About 10 days later, or 40 days after initial fertilization, the "eyed up" eggs hatch into baby fish, known as "alevin".
The eggs may be scattered, deposited or buried, depending on the species. Scattered eggs either fall to the substrate, float to the surface or stick to plants, rock or whatever else they come in contact with.
The Atlantic cod lays its eggs in the open water. The eggs do not sink, but float within the water column.
When a male betta fish is ready to breed, he will create a bubble nest. These bubble nests will float on the very top of the tank, and appear like a cluster of small bubbles.
Nematode eggs will float at an SG of more than 1.15. Eggs from trematodes and cestodes will float at an SG from 1.35 and higher. However, high SGs of parasite ova bear some disadvantages.