Aquatics Unlimited: Articles: Blue Sheets - Freshwater Fish Selection and Care
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"Blue Sheets" - Freshwater Fish Selection and Care

Tropical fish are perhaps the easiest of all pets to maintain. There are, however, certain problems that may occur, causing new hobbyists, as well as unsuccessful existing hobbyists, to become frustrated and upset with this fascinating hobby. The purpose of this writing is to give the new hobbyist, and experienced hobbyists as well, a simple, concise guide to follow. The data in this guide are based upon years of experience, under all conditions, with several hundred different species of fish kept in water from our area, and therefore, give a very good idea of how a fish is likely to act (exceptions are always possible, but not common).

Most beginning hobbyists have the same objective in mind: they want to have an aquarium with a nice assortment of colorful fish. Unfortunately, selecting fish is not quite as easy as buying an assortment of candy or bakery. When dealing with live fish, some knowledge of the subject has to be obtained before problems start.

This guide is divided into four (4) parts:

  • PART 1 - a general discussion about steps to take before buying fish
  • PART 2 - a list of traits, habits and requirements of most fish (this may seem extensive, but must be complete to be useful)
  • PART 3 - one hundred plus popular fish species, each with its own special requirements from PART 2
  • PART 4 - some of the more common problems that may occur after the fish are in the aquarium

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Part 1

Make sure that the following list has been checked before you consider buying any fish:

  1. The aquarium and equipment should be set up as directed and placed in their final location (this should not be in front of a window, since excessive light, and/or rapid temperature changes can cause trouble. Do not use soaps or cleaners on anything.
  2. Add one tablespoon of aquarium salt and on teaspoon of "Start Right" (an excellent water conditioner and chlorine remover) to each five gallons of water.
  3. Make sure that the filter is working properly and that the temperature is between 76-80o F (25-27o C).
  4. Allow the aquarium to "stabilize" for at least 24 hours (48 hours is even better).

After the 24-48 hour stabilization period, it is time to obtain your fish. The following two sections of this writing will hopefully make your choice of fish considerably less complicated and more problem free.

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Part 2

Each species of fish has a unique set of habits and requirements that must be considered when numerous species of fish are mixed together into "community" aquariums. The word "community," however, is the most overused and least understood word in this hobby. Almost all fish are community fish. Compatibility depends upon how fish are mixed. Totally "peaceful" fish are community fish are often, but not always, weaker or more sensitive than more assertive species. Some very popular fish can be poor first fish selections for a beginner. These fish are neons, cardinals, black angels, and many livebearers (see PART 4 discussion on fungus and bacteria for livebearer problems). After a beginner becomes skilled at aquarium management and maintenance, these species will not be nearly as difficult to keep healthy. May barbs, rasboras, danios, and larger tetras make excellent starter fish.

A mildly "aggressive" community aquarium can be set up as an alternative to a peaceful community, and will often give you hardier, more active and more interesting fish, with far fewer problems. Most fish react better if purchased in groups of three or more, than they do in "pairs." In addition to your regular fish, at least two scavengers and on algae eater should be used for each ten gallons of water in your aquarium.

The following page is a list of the more common and important traits that should be considered when mixing fish. The fish that are followed by an asterisk* are generally excellent starter fish and will usually mix well together.

Gary Kenley was kind enough to convert the following table to spreadsheet form.
Download the Excel® version ( - about 16k)
Download the Quattro Pro® version ( - about 14k)
Download the Text version (fishchrt.txt - about 11k)

  • a. Peaceful - has not been known to bother any other fish
  • b. Spirited - normally peaceful, but may chase slow species
  • c. Mildly aggressive - should not be kept with slow or timid fish
  • d. Aggressive - should be kept with larger active fish
  • e. Pugnacious - not acceptable in community tanks
  • f. Vulnerable - likely to be harassed, picked on, or fin nipped by other fish, sonmetimes even by otherwise peaceful species
  • g. Changeable - may be mixed with other fish when young, but may become more aggressive when older, and may eat smaller fish
  • h. Hardy - tolerant to various water conditions and not commonly affected by hard to treat diseases
  • i. Disease prone - subject to hard to treat diseases
  • j. Touchy - subject to water condition problems (extreme pH, hardness, ammonia, etc.)
  • k. Subject to "Ich" - susceptible to the common, but very easily controlled parasite, Ich
  • l. Livebearer - requires salt, up to a teaspoon per gallon, and some vegetable diet (condition food). Livebearer babies will be eaten if not separated.
  • m. Warm water - requires water of 84-86o F (29-30o C) to remain in top condition
  • n. Temperate - will tolerate or prefer cooler water, but will do well at normal tropical temperatures - 76-80o F (25-27o C)
  • o. Cool water - should be kept in water 68-72o F (20 - 22o C)
  • p. Brackish - could be kept with more salt (sea salt) in water than normal tropicals, although 1 TBS per 5 gallons is sufficient
  • q. Jumpers - tanks should be completely covered
  • r. Intolerance to malachite green - is weakened or dies when treated with the otherwise very effective "Ich" medication, malachite green. Ich medications range from useless (too slow or too weak) to dangerous (killing tetras, catfish, etc.) Please ask us how to treat this disease. The numerous ich medications on the market can be very confusing and can vary greatly in quality. (See discussion on Ich, page 4.)
  • s. Fast growth - may become much larger than purchased size
  • t. Plant eater - will probably destroy and/or eat most aquarium plants
  • u. Risky - notoriously weak from shipment and/or fluctuating water properties - may be frustrating to attempt, but worthwhile if successful
  • v. Special treatment - a clerk should be consulted to find out the unique properties of these fish
  • w. Sensitive to well water - these fish may not like certain well water - caution is advised and experimentation is necessary as this sensitivity may vary from on well to another. (Any tap water not from Lake Michigan is considered well water. See duscussion on well water, Page 4.)
  • x. Algae eater - will eat unsightly algae off rocks, plants, glass etc.
  • y. Scavenger- will eat troublesome uneaten food particles that will otherwise cloud and pollute water (at least two (2) scavengers/10 gal.)
  • z. Special food - may require a special diet to remain healthy

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Part 3


guppies (common) a,h,l
guppies (fancy) a,f,h,l
half beak a,f,j,l,q.z
mollies b,i,l,q
platies a,i,l,q
swordtails b,i,l,q


giant b,h,q *
leopard b,h,n,q *
pearl b,h,n,q *
zebra b,h,n,q *


checker a,h *
cherry a,i
clown b,i,q
gold a,h *
red top b,h *
rosy b,h *
tiger c,h *
tinfoil b,h,q,s,t


black b,h *
black line a,h *
black neon a,i,k,r,u,w
black phantom b,h
bleeding heart b,i
blind cave c,h,t *
bloodfin b,h *
buenos aires b,h,t *
cardinal a,i,k,r,u,w
congo b,h
emperor b,j
exodon paradoxus d,h,t
glass fish a,h
glo lite a,h *
hatchet a,i,k,r,u,w
head & tail light a,h *
lemon a,i,k,r,u,w
leporinus d,g,h,q,s
neon (jumbo) a,i,j,k,r,w
neon (small) a,f,i,j,k,r,w
pacu d,g,h,s,t
pencil fish a,j,u
pirahna e,h,s,v,z
red eye b,h *
red minor b,h *
serpae b,h *
silver dollar a,h,k,s,t
silver tip c,h
von rio b,h *
white cloud a,h,n
white skirt b,h *


acara c,g,h,s
african (haplochromis) c,g,h,s,t
african (pseudotropheus) e,g,h,q,t,v
angelfish b,f,i,j,s,u,w
convict c,g,h
discus a,f,i,j,k,m,u,w,
festivum b,g,h,k,s
firemouth c,g,h,s
jack dempsey d,g,h,s
jewel d,h
jurupari b,g,h,s,t
kribensis b,h
mozambique b,g,h,s
oscar c,g,h,k,s
rams a,i,j,m,u,w,z
red devil d,g,h,s,t
severum b,g,j,k,s,t,w


heteromorpha a,h *
redtail a,h *
scissortail a,h *


australian a,h *
celebese a,f,z
fancy (red, turquoise,etc,) c,h


betta (female) c,i,z
betta (male) c,f,h,v,z
blue b,g,h,q *
dwarf a,h,k *
giant b,g,h,q
gold b,g,h,q
kissing b,g,h,k
opaline b,g,h,q *
paradise c,h,n
pearl a,f,i,q
platinum b,g,h,q
thick lip b,g,h,q


algae eater b,g,h,q,s,x
channel a,g,n,r,s,y
corydoras (tank raised) a,h,y *
corydoras (wild) a,i,j,w,y
phantom glass a,j,r,w
pictus (false angelicus) b,g,k,r,w,y
plecostomus a,h,s,w,x,y
shovelnose c,g,q,s,z
stick fish a,j,x
synodontis b,h,k,r,y
upside down b,h,k,r,y
whiptail a,h,x,y


bala (tricolor) a,h,q
black d,g,h,q,s
high fin bull b,g,k,r,s,w,y
irridescent b,j,k,q,r,s,w
rainbow b,g,h,q,s,x
redtail b,g,h,q,s,x


clown b,h,k,q,y
horseface a,h,y
kuhlii a,i,q,y
lohachata b,h,q,y *
skunk b,h,k,q,y
tiger d,h,q,y
weather a,h,q,y *


african b,h,z
black ghost b,h,z
brown ghost b,f,j,z
clown c,g,h,s,z
glass a,f,i,j,u,z


arawana b,g,h,q,s,v,z
archer b,h,p,q
baby whale c,i,k,q,r,z
bumble bee goby c,j,p
butterfly fish b,h,q,z
elephant nose b,i,k,q,r,z
flounder a,h,y
goldfish (common) b,f,h,o,s,t,y
goldfish (domestic) b,f,h,n,s,t,y
goldfish (imported) b,f,i,n,s,t,y
killifish j,o,v
koi b,h,n,q,s,t,y
leporinus c,g,h,q,s
mono c,h,p,s
puffer d,h,k,p,z
rope eel a,j,q,z
scat c,i,p,s,t,z
snakehead e,h,k,q,r,s
spiny eel a,h,q,z


crayfish d,h,n,t,y
fiddler crabs b,j,p,q,u,v,y
frog (african clawed) b,g,h,q,s,x
frog (dwarf) a,j,q
ghost shrimp b,h,y
newts (eastern) a,h,n,q,v,z
newts (other) b,h,n,q,v,z
snails (apple) a,f,h,n,q,t,x,y
snails (mystery) a,f,h,n,q,x,y
tadpole a,f,h,n,x,y

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Part 4

Some problems will happen sooner or later in almost any aquarium, therefore it is a wise idea to learn now to recognize and handle them before they occur. Some common problems are:

ICH: Short for the protozoan Ichthyophthirius, Ich is the most common disease found in the aquarium. Ich should be carefully watched for whenever new fish are added to an aquarium. The first signs are clamped fins and scratching (against objects) followed shortly by small, round white spots usually seen first on fins or tails. (These spots are always about the size of a grain of salt.) Fish get ich much like people would get a cold (chill, bad diet, stress, etc.) Ich is usually present in all aquariums (including yours) waiting for a chilled or otherwise stressed fish to use as a host. In other words, a new fish usually gets ich in your aquarium. Few fish should ever be lost because of Ich. It is easily treated by using one drop per gallon (actually about 8 drops in a ten gallon tank) when it is first noticed. Use "Ich Cure" made by Aquatrol Co.. Fish that are sensitive to ich cure (Line R - PART 2) should be treated with two half doses about 12 hours apart. If fish with ich are not treated, the disease will quickly spread and many fish will eventually die. Aquariums kept at steady temperatures (ideally 80o F - 27o C ) will have fewer cases of ich than cooler aquariums.

FUNGUS AND BACTERIA INFECTIONS: Although livebearers are a colorful and interesting group of fish, they are very susceptible to fungal and bacterial related diseases when not handled correctly. These problems are not as easy to treat as ich, but they often can be easier to see. Large white patches, rotted tails or fins, white film, white lips or eyes, and cottony clumps are some things to look for. Treatment should be started as soon as possible, but since these problems are not easy to diagnose correctly it would be best to check with us for the correct remedy. (Ich Cure will not treat fungus or bacterial infections).

CLOUDY WATER: Cloudy water will occur in three different ways. If water turns cloudy as soon as an aquarium is filled, it is due to improperly rinsed gravel. If an aquarium turns slightly cloudy a day or two after filling, it is usually due to harmless bacteria that will soon disappear. If, however, and your aquarium turns cloudy anytime thereafter, it is almost always due to overfeeding, causing pollution. Usually a few extra scavengers and much less food will reverse this problem.

ALGAE: Excessive green algae is caused from too much light, either natural or artificial, and can be controlled simply by reducing either the strength or duration of the light source. Overfeeding will stimulate algae growth. Live plants that are growing will usually keep algae under control, but dead plants will aid algae growth. A few green dots on the glass are normal and these can be easily removed about every two weeks with an algae scraper. Algae eaters will clean algae off rocks and plants.

WATER QUALITY: Aquariums can be crystal clear, but still contain fish in deep trouble . Poor water quality is often the problem. Possibly more fish are lost to poor water conditions than to diseases. Fish that breathe rapidly, dash about, stay at the surface or show red gills or blotches, may be reacting to poor water quality. Paint or varnish vapors, ammonia based window cleaners, soap, unsafe rocks, shells or coral, bug sprays, and plastic plants or ornaments not made for aquarium use, can all kill fish if present in your aquarium. Biological or chemical problems can also kill fish without being obvious. These problems include low dissolved oxygen (from overcrowding, overfeeding or poor aeration), high ammonia (from infrequent water changes or overcrowding), excessive chlorine (from adding too much untreated tap water), overmedication, and plugged undergravel filter plates or stems. In all cases of severe water pollution, the cause must be removed and a major water change should be made (be sure to use a good water conditioner such as "Start Right" and water of the same temperature).

CITY WATER: (Lake Michigan): City water is safe for almost all tropical fish if "Start Right" is used before the fish are introduced and if the temperature is correct. Normally, a 10% water change every two weeks will keep city water aquariums in good shape. Adding water only to replace evaporated water is not good enough.

WELL WATER: (Not from Lake Michigan): Because water from deep in the earth or from springs is chemically different from lake or river water that tropical fish are accustomed to, some special handling of new fish is advised. Each well is different and must be considered accordingly. Usually a 50-50 mix of hard and "soft" water is good to begin with. After some experience, you may have reason to use more or some or all of either. Before releasing new fish, small amounts of your well water should be added at ten minute interdded at ten minute intervals to their bags. This will help them adjust to your water differences. Fish followed by an "h" (without a "j" or "w") in PART 3 are good choices. Using chemicals to reduce the pH of your aquarium is usually unnecessary and possible hazardous. pH levels in most of our area water are somewhat high (7.4-7.8) but not dangerous. Unfortunately, well water, hard or soft, cannot become Lake Michigan water, and although well water is fine for most hardy fish, some city water may have to be used to keep touchier species healthy.

On rare occasions, when city water quality is low, ammonia is added to city water systems to keep extra amounts of chlorine more effective. When this high chlorine odor is detected, large water changes (over 10%) are not recommended.

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