AboutMichael Freynet Expertise I can answer most questions on freshwater aquariums involving the biological cycle, live plants, fish compatibility, stocking quantity, feeding, filtration, aeration, water chemistry, and cleaning. I am still learning about some certain diseases and parasites but am more than willing to research any questions that I do not know.
Experience I have owned multiple freshwater fish tanks over the years. I also help maintain other people’s freshwater fish tanks. I am currently a college student at Minnesota State University Moorhead for a major in Biology and a minor in Zoology. I'm also currently employed at Petco.
Question QUESTION: I am a beginner and have just bought my first tank. Its 70litres (18gallons I think) but I dont fill it right to the top. I have a cool water setup and have already put the gravel, pump and water in for the tank to run fishless for a few days. Its been running for 3 days now and I would like to get fish tomorrow but am not sure about what to get and how many of each kind. I dont want fish that omit too much waste and I want them to be nice to look at. I have done quite a bit of research and have these options on my list: Cherry Barbs, Glowlight Tetras, Harlequin Rasboras, White Clouds, Zebra Danios, Fancy Guppies and Ghost shrimp. I would like there to be a bottom feeder as well and therefore think the Ghost Shrimp would work. I would prefer having smaller fish so I can have more in the tank. Please advise me on which fish and how many of each to choose? Thanks so much!
ANSWER: Hi Kim,
Well I'm glad you took the time to do your research before investing in your fish! Remember with tropical freshwater fish the general rule is one inch of fish per one gallon of water. Remember to only get three fish MAXIMUM per week and after you get your first three to wait at LEAST two weeks before you add any more to your tank otherwise you are risking them all dying of toxicity. All of the fish you mentioned are great candidates for a 18 gallon tank as they are all friendly and small fish.
Remember that all of the fish you mentioned are schooling fish so allow me to list you the minimum optimal schooling size for each of the fish listed. Ill also list the fish from top to bottom from most "hardy" to most sensitive.
Knowing that I would probably start off with either the Danios or the Clouds first since they are much more suitable for starting your tanks cycling. Once the tank is established (cycling usually takes between 5-7 weeks) I would decide on if you want to get the Harlequins or the Glowlights as since they require the largest schools I would only choose one and not both as your aquarium is not very large. In all honesty I would stay away from Fancy Guppies unless you plan to have only males or only females. If you mix the genders they will breed and risk overpopulating your tank. Although Ghost Shrimp are always a nice subtle addition to most aquariums if you are looking for a reliable bottom feeder consider a trio of Corydoras. They are cute, peaceful, stay small, and are excellent eaters. They are schooling fish (but unlike other schooling fish they will school with other Corydora species so you can even have three different types) so keep no less than three of them if you plan to ever attain any.
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QUESTION: Thanks Michael! Yours was the best response I've received and I feel so much better knowing I have some confirmed direction! I do have a cool water tank and somebody else said that these fish need to be in a warm tank... is this imperative? I will take your advice and have narrowed it down to the 3 Danios. 3 white clouds, 3 cherry barbs (and would 6 rasboras also fit in at a later stage?) What type of corydoras should I get? I am not familiar with that species... Once more Thanks! :)
Answer Hello again,
I guess I didn't realize that you mentioned it was a cool water setup. What do you mean by that exactly? As in your keeping it at around room temperature(68-72 degrees F?) Although Danios and White Clouds can easily handle the cooler water temperatures keep in mind they are still tropical fish and a temperature of 78-80 degrees F is ideal for tropical fish. Another good reason to get a heater for your tank(cold water or not) is to help stabilize the water temperature. Fluctuating temperatures constantly even within a few degrees can be very stressful to your fish. Remember fish are ectotherms and cannot control their body temperatures. By warming up the water to tropical temperatures their metabolisms will speed up which will result in them having stronger immune systems, eating better, and developing brighter colors.
Remember the one inch of fish per gallon of water rule. For example Glowlight Tetras and Harlequin Rasboras adult sizes are just a bit over an inch so you could eventually fit 18 in an 18 gallon tank. Danios adult sizes are at 2 inches so you could fit 9 in a 18 gallon tank.
There are many species of Corydoras. The most common varieties you will see are the Bronze, Emerald, Albino, and Peppered(also knows as Paleatus). They are the four most hardy of Cory species and I would recommend choosing from them.
