What is the Lateral Line?
The lateral line is a tube running
just below the surface of the skin along the sides of the body, usually
marked externally by a series of pores that open out through the scales.
View these fish anatomy
diagrams from the Badman's Tropical Fish website to get an idea of
where the lateral line is located. Even though these diagrams are of freshwater
fishes, the lateral line relates in the same way to all fish species. It
is a very important sensory organ. It can detect minute electrical currents
in the aquarium water and also functions as a kind of echo location system
that helps fish to identify their surroundings. There is usually only a
single lateral line on each side of the body, but many variants of the
typical lateral line may occur. For example, on the sides of the
Belonidae
(Needle Fish), Hemiramphidae (Half-Beak Fish),
Exocoetidae
(Flying Fish), and a few other fish families, the lateral line runs very
low on the sides. On some species the lateral line may also be incomplete,
in which case it stops short of the base of the caudal fin. It may also
be interrupted, meaning that it ends and then recommences after a gap,
perhaps several scale rows lower down on the body, as in some of the
Labridae
(Wrasse)
species. Strangely enough, in a fairly large number of families the lateral
line is absent altogether.
Possible Causes
There are many "theories" as to
why this disease occurs, but there seems to be no single definitive
answer that can be pinpointed or solely connected to it. Many of the contributing
theories include stray voltage in the aquarium, poor water quality and
environmental conditions, high nitrate levels, lack of vitamins and poor
nutrition, stress, parasitic infestation (a protozoan, Octomita necatrix),
using carbon, and that some fish may just be genetically pre-disposed to
this disease condition, such as Tangs
& Surgeonfishes (refer to sixth discussion down).
Treatment
Most of the above possible causes
can be easily addressed. Stray voltage induces stress, so adding a grounding
probe to the aquarium is a wise thing to do in any case. For poor water
quality and environmental issues, follow good regular aquarium maintenance
routines. Reduce and eliminate any other stress inducing factors, correctly
diagnosis for parasites and always feed fishes foods that any particular
species require in their diets.
Using over the counter medications do not seem to do much in treating this disease. However, those that contain antibiotics can help to treat for secondary infections. From all the research we have done, no matter what the actual "cause" may be, it appears that improving water quality and providing supplemental vitamins and adequate nutrition are key elements in "treating" HLLE. Many aquarists have had great success in reversing the effects of this disease by providing the fish with supplemental vitamins, such as A, D, E or B's, as well as iodine. This can be accomplished by feeding them foods soaked in Selcon, Zoe or other liquid vitamins, providing algae eating species with vitamin-rich live plant sources, such as macroalgae, i.e. Caulerpa (refer to the third discussion down) and adequate live rock growth, and even by [feeding a diet of broccoli supplemented with peas and other prepared foods.
For more information about this disease, refer to our HLLE Disease Resources.
