#227: Aquarium’s Water


Assalamualaikum w.b.t. What is the ruling of aquarium’s water? It’s my routine to clean my aquarium every week and surely every time some of the water will spill on the floor. Is it considered as najis because the aquarium’s water is mixed with the fish’s excrements and if this is so, how should I wash it? Thank you.


Waalaikumussalam wrt. wbt.,

Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.

We begin with the statement of Allah SWT:

إِنَّ اللَّهَ يُحِبُّ التَّوَّابِينَ وَيُحِبُّ الْمُتَطَهِّرِينَ

“Indeed, Allah loves those who are constantly repentant and loves those who purify themselves.” [1]

Al-Syaukani said the meaning of the above verse is that Allah SWT loves those who repent from his sins and purify themselves from janabah and hadas. [2] In other words, Allah SWT loves His slaves who always repent with istighfar and purify and distance themselves from dirty and disgusting acts. [3]


Islam emphasizes matters of purification and cleanliness. Likewise, people are naturally inclined towards cleanliness and would avoid any filth. Since Islam is an innate religion, then it is natural for it to command its followers to purify themselves and take care of their cleanliness. The Prophet PBUH also stated:

الطُّهُورُ شَطْرُ الإِيمَانِ

“Purity is half of iman (faith).” [4]

Likewise, taking care of animals such as fish is a permissible and commendable act. However, taking care of animals is a responsibility. Furthermore, in fiqh books, this discussion is included under the title of sustenance for pets such as fishes, where they should be provided with suitable shelter and food. While for other animals (other than fishes) there are three matters which are shelter, food and drink. [5]

Types of najis

Najis is divided into three which are Mukhaffafah najis (minor), Mutawassitah najis (moderate) dan Mughallazah najis (major).

  • Mughallazah najis are dogs and swine and anything from them.
  • Mukhaffafah najis is the urine of a baby boy who only suckles from his mother and is not more than two years old.
  • Mutawassitah najis is najis other than both previously stated najis. For example, urine, animals’ excrements and blood. [6]

Aquarium’s water

First, we should know that according to madhhab Syafi’I any animal excrement, droppings and urine is considered as najis. This is based on a narration of Ibn Mas’ud RA, he said:

فأتيتُه بحجرَيْن وروْثةٍ فأخذ الحَجرَيْن وألقى الرَّوْثةَ وقال: إنَّها رِكسٌ

“So, I brought him two stones and a piece of dung. He took the two stones and threw the dung away, saying: ‘It is impure.'” [7]

Likewise, al-Nawawi also said that all types of excrement and urine are considered as najis regardless of whether the animal is permissible to be eaten or otherwise. This ruling applies to the excrements of fish and grasshoppers as well as other animals or insects that don’t have flowing blood such as mosquitoes. Thus, its filth (excrement) and urine, both are considered najis. This is the opinion in madhhab Syafi’I and decided by syafi’I scholars from Iraq and a group of scholars from Khurasan. However, there is a weak opinion of Shafiite scholars from Khurasan regarding the purity of filth (excrements) of fish and grasshoppers as well as other animals without flowing blood. [8]

Thus, aquarium water is usually mixed with the excrements of fish. According to the final opinion, if the water in the aquarium is a little (less than two qullah) and contains excrements (fish’s excrements), then the water is ruled as najis and is categorized as mutawassitah najis.

Methodology of purifying Mutawassitah najis

Regarding Mutawassitah najis, Habib Hasan bin Ahmad al-Kaff stated that it is divided into two categories which are hukmiyyah (حكمية) and ‘ainiyyah (عينية). Hukmiyyah is a najis that isn’t visible because of its smell, color or taste. The methodology of cleaning it is to wash the place where the najis came into contact with flowing water. While ‘ainiyyah is najis which is visible or one of its attributes such as smell, color and feel is present. It is washed until all of its attributes (smell, taste and color) is gone. If the najis can be washed with a single washing, then it is sufficient. However, it is sunnah for him to wash for a second or third time.

Likewise, if the najis cannot be washed with a single washing, then it is obligatory for him to wash it a second time. And if it is still not gone, it is obligatory to be washed for the third time.  If the najis cannot be washed after the third washing even with the help of cleaning agents such as soap and others, then this situation is named as a difficult situation (حالة التعسر). [9]

Syeikh al-Islam Zakaria al-Ansari stated that the examples of hukmiyyah najis are like dried urine of which its traces or characteristics is no longer visible. Thus, the way to clean and purify it is by washing it with flowing water once. As for ‘ainiyyah, it is obligated to wash until the smell, taste and color are gone, except if there is a difficulty to wash or remove one of the two characteristics whether it is the color or smell. Hence, in this matter, it is not obligatory to remove it and it is considered pure. However, if both these characteristics are present together (smell and color) on the place, then it is obligatory to wash it until both are gone, for they are strong evidence that the ‘ain of the najis is still there just like its attribute or characteristic that is shown by taste. [10]

According to the above arguments and discussions, we conclude that originally aquarium’s water that is small in volume (less than two qullah) and is mixed with the excrements is categorized as mutawassitah najis (moderate). Thus, if the water splashed or spilt, then it should be cleaned following the methodology of purifying mutawassitah najis. However, if the splash is too little that one couldn’t even see or due to the fact that it is difficult to avoid, especially during the cleaning process, then it is included in the forgiven najis by syarak according to the Umm al-Balwa method.

However, it is best if the cleaning and changing the water for the aquarium process is performed outside or first layer the floor with cloths or others (to avoid the water from spilling on the floor) to avoid the khilaf which is mustahab (encouraged).

May Allah SWT grant us a clear understanding in practising this religion. Amin.

Wallahu a’lam.


[1] Surah al-Baqarah: 222

[2] See Zubdah al-Tafasir min Fath al-Qadir by al-Asyqar, pg. 44.

[3] See Tafsir al-Muyassar, pg. 35.

[4] Narrated by Muslim (223)

[5] See al-Iqna‘ by al-Khatib al-Syirbini, pg. 637-640.

[6] See al-Fiqh al-Manhaji, 1/40-41.

[7] Narrated by al-Tirmizi (17); Ibn Majah (314); Ahmad (3685)

[8] See al-Majmu‘ Syarh al-Muhazzab, 2/550.

[9] See al-Taqrirat al-Sadidah, pg. 135.

[10] See Fath al-Wahhab, 1/25; Kasyifah al-Saja, pg. 182-184.

[11] See Kasyifah al-Saja, 182-183.

[12] See al-Taqrirat al-Sadidah, pg. 136.

[13] See al-Fiqh al-Manhaji, 1/43.